ELECTRICITY FOR THE FARM THE MACMILLAN COMPANY HEW YORK BOSTON CHICAGO DALLAS ATLANTA SAN FRANCISCO MACMILLAN & CO., LIMITED LONDON BOMBAY CALCUTTA MELBOURNE THE MACMILLAN CO. OF CANADA, LTD. TORONTO ELECTRICITY FOR THE FARM LIGHT, HEAT AND POWER BY INEXPENSIVE METHODS FROM THE WATER WHEEL OR FARM ENGINE BY FREDERICK IRVING ANDERSON AUTHOR OP " THE FABMEB OP TO-MOBBOW," ETC., BTC. fork THE MACMILLAN COMPANY 1916 AU rieht* reserved COPYBIQHT, 1915 BY THE CURTIS PUBLISHING COMPANY The Country Gentleman COPYRIGHT, 1915 BY THE MACMILLAN COMPANY Set up and electrotyped. Published April, 1915. Reprinted December, 1916 PREFACE THIS book is designed primarily to give the farmer a practical working knowledge of electricity for use as light, heat, and power on the farm. The electric generator, the dynamo, is explained in detail; and there are chapters on electric transmission and house-wiring, by which the farm mechanic is enabled to install his own plant without the aid and expense of an expert. With modern appliances, within the means of the average farmer, the generation of elec- tricity, with its unique conveniences, becomes automatic, provided some dependable source of power is to be had such as a water wheel, gasoline (or other form of internal combustion) engine, or the ordinary windmill. The water wheel is the ideal prime mover for the dynamo in isolated plants. Since water-power is run- ning to waste on tens of thousands of our 451825 vi PREFACE farms throughout the country, several chap- ters are devoted to this phase of the subject: these include descriptions and working di- agrams of weirs and other simple devices for measuring the flow of streams; there are tables and formulas by which any one, with a knowledge of simple arithmetic, may deter- mine the power to be had from falling water under given conditions; and in addition, there are diagrams showing in general the method of construction of dams, bulkheads, races, flumes, etc., from materials usually to be found on a farm. The tiny unconsidered brook that waters the farm pasture frequently possesses power enough to supply the farm- stead with clean, cool, safe light in place of the dangerous, inconvenient oil lamp; a small stream capable of developing from twenty- five to fifty horsepower will supply a farmer (at practically no expense beyond the original cost of installation) not only with light, but with power for even the heavier farm opera- tions, as threshing; and in addition will do the washing, ironing, and cooking, and at the PREFACE vii same time keep the house warm in the coldest weather. Less than one horsepower of energy will light the farmstead; less than five horse- power of energy will provide light and small * power, and take the drudgery out of the kitchen. For those not fortunate enough to possess water-power which can be developed, there are chapters on the use of the farm gasoline engine and windmill, in connection with the modern storage battery, as sources of electric cur- rent. It is desired to make acknowledgment for illustrations and assistance in gathering mate- rial for the book, to the editors of The Country Gentleman, Philadelphia, Pa.; The Crocker- Wheeler Company, Ampere, N. J.; The General Electric Company, Schenectady, N. Y.; the Weston Electrical Instrument Company, of Newark, N. J.; The Chase Turbine Manufacturing Company, Orange, Mass.; the C. P. Bradway Machine Works, West Stafford, Conn.; The Pelton Water Wheel Company, San Francisco and New viii PREFACE York; the Ward Leonard Manufacturing Company, Bronxville, N. Y.; The Fairbanks, Morse Company, Chicago; and the Fitz Water Wheel Company, Hanover, Pa. TABLE OF CONTENTS PAGE INTRODUCTION XVU PART I WATER-POWER CHAPTER I A WORKING PLANT The "agriculturist " An old chair factory A neighbor's home-coming The idle wheel in commission again Light, heat and power for nothing Advantages of electricity 3 CHAPTER H A LITTLE PROSPECTING Small amount of water required for an electric plant Exploring, on a dull day A rough and ready weir What a little water will do The water wheel and the dynamo Electricity consumed the instant it is produced The price of the average small plant, not counting labor 22 CHAPTER m HOW TO MEASURE WATER-POWER What is a horsepower? How the Carthaginians manu- factured horsepower All that goes up must come ix x TABLE OF CONTENTS PAGE down How the sun lifts water up for us to use Water the ideal power for generating electricity The weir Table for estimating flow of streams with a weir Another method of measuring Fig- uring water horsepower The size of the wheel What head is required Quantity of water neces- sary 32 CHAPTER IV THE WATER WHEEL AND HOW TO INSTALL IT Different types of water wheels The impulse and the reaction wheels The impulse wheel adapted to high heads and small amount of water Pipe lines Table of resistance in pipes Advantages and dis- advantages of the impulse wheel Other forms of impulse wheels The reaction turbine, suited to low heads and large quantity of water Its advan- tages and limitations Developing a water-power project: the dam; the race; the flume; the penstock; and the tailrace Water rights for the farmer 56 PART II ELECTRICITY CHAPTER V THE DYNAMO; WHAT rr DOES, AND HOW Electricity compared to the heat and light of the sun The simple dynamo The amount of electric energy a dynamo will generate The modern dynamo Measuring power in terms of electricity The volt The ampere The ohm The watt and the kilo- TABLE OF CONTENTS xi PAGE wa tt Ohm's Law of the electric circuit, and some examples of its application Direct current, and alternating current Three typjes of direct-current dynamos : series, shunt, and compound ............ 89 CHAPTER VI WHAT SIZE PLANT TO INSTALL The farmer's wife his partner Little and big plants Limiting factors Fluctuations in water supply The average plant The actual plant Amount of current required for various operations Standard voltage A specimen allowance for electric light Heating and cooking by electricity Electric power: the electric motor .............................. 121 CHAPTER VH TRANSMISSION LINES Copper wire Setting of poles Loss of power hi trans- mission Ohm's Law and examples of how it is used in figuring size of wire Copper- wire tables Examples of transmission lines When to use high voltages Over-compounding a dynamo to overcome transmission loss .............................. 153 CHAPTER WIRING THE HOUSE The insurance code Different kinds of wiring described Wooden moulding cheap and effective The dis- tributing panel Branch circuits Protecting the circuits The use of porcelain tubes and other in- xii TABLE OF CONTENTS PAGE sulating devices Putting up chandeliers and wall- brackets "Multiple" connections How to connect a wall switch Special wiring required for heat and power circuits Knob and cleat wiring, its advan- tages and disadvantages 172 CHAPTER IX THE ELECTRIC PLANT AT WORK Direct-connected generating sets Belt drive The switchboard Governors and voltage regulators Methods of achieving constant pressure at all loads : Over-compounding the dynamo; A system of re- sistances (a home-made electric radiator) ; Regulat- ing voltage by means of the rheostat Automatic devices Putting the plant in operation 192 PART III GASOLINE ENGINES, WINDMILLS, ETC. THE STORAGE BATTERIES CHAPTER X GASOLINE ENGINE PLANTS The standard voltage set Two-cycle and four-cycle gasoline engines Horsepower, and fuel consump- tion Efficiency of small engines and generators Cost of operating a one-kilowatt plant 217 CHAPTER XI THE STORAGE BATTERY What a storage battery does The lead battery and the Edison battery Economy of tungsten lamps for TABLE OF CONTENTS riii PAGE storage batteries The low-voltage battery for electric light How to figure the capacity of a bat- tery Table of light requirements for a farm house Watt-hours and lamp-hours The cost of storage battery current How to charge a storage battery Care of storage batteries 229 CHAPTER XH BATTERY CHARGING DEVICES The automatic plant most desirable How an automobile lighting and starting system works How the same results can be achieved in house lighting, by means of automatic devices Plants without automatic regulation Care necessary The use of heating de- vices on storage battery current Portable batteries An electricity "route" Automobile power for lighting a few lamps 250 ILLUSTRATIONS Even the tiny trout brook becomes a thing of utility as well as of joy Frontispiece Facing page Farm labor and materials built this crib and stone dam . . 17 Measuring a small stream with a weir 23 Efficient modern adaptations of the archaic undershot and overshot water wheels 59 A direct-current dynamo or motor, showing details of construction 92 Details of voltmeter or ammeter 128 Instantaneous photograph of high-pressure water jet be- ing quenched by buckets of a tangential wheel .... 194 A tangential wheel, and a dynamo keyed to the same shaft the ideal method for generating electricity . . 194 A rough-and-ready farm electric plant, supplying two farms with light, heat and power; and a Ward Leonard-type circuit breaker for charging storage batteries . . . 244 INTRODUCTION THE sight of a dozen or so fat young horses and mares feeding and frolicking on the wild range of the Southwest would probably in- spire the average farmer as an awful example of horsepower running to waste. If, by some miracle, he came on such a sight in his own pastures, he would probably consume much time practising the impossible art of "creas- ing" the wild creatures with a rifle bullet- after the style of Kit Carson and other free rovers of the old prairies when they were in need of a new mount. He would probably spend uncounted hours behind the barn learning to throw a lariat; and one fine day he would sally forth to capture a horsepower or two and, once captured, he would use strength and strategy breaking the wild beast to harness. A single horsepower animal will do the work of lifting 23,000 pounds one foot in one minute, providing the animal is rvu xviii INTRODUCTION young, and sound, and is fed 12 quarts of oats and 10 or 15 pounds of hay a day, and is given a chance to rest 16 hours out of 24 providing also it has a dentist to take care of its teeth occasionally, and a blacksmith chiropodist to keep it in shoes. On the hoof, this horsepower is worth about $200 unless the farmer is looking for something fancy in the way of drafters, when he will have to go as high as $400 for a big fellow. And after 10 or 15 years, the farmer would look around for another horse, because an animal grows old. This animal horsepower isn't a very efficient horsepower. In fact, it is less than three- fourths of an actual horsepower, as engineers use the term. A real horsepower will do the work of lifting 33,000 pounds one foot in one minute or 550 pounds one foot in one second. Burn a pint of gasoline, with 14 pounds of air, in a gasoline engine, and the engine will supply one 33,000-pound horsepower for an hour. The gasoline will cost about 2 cents, and the air is supplied free. If it was the air that cost two cents a pound, instead of the INTRODUCTION xix gasoline, the automobile industry would un- doubtedly stop where it began some fifteen years ago. It is human nature, however, to grumble over this two cents. Yet the average farmer who would get excited if sound young chunks and drafters were running wild across his pastures, is not inspired by any similar desire of possession and mastery by the sight of a brook, or a rivulet that waters his meadows. This brook or river is flowing down hill to the sea. Every 4,000 gallons that falls one foot in one minute; every 400 gallons that falls 10 feet in one minute; or every 40 gallons that falls 100 feet in one minute, means the power of one horse going to waste not the $200 flesh- and-blood kind that can lift only 23,000 pounds a foot a minute but the 33,000 foot-pound kind. Thousands of farms have small streams in their very dooryard, capable of developing five, ten, twenty, fifty horse- power twenty-four hours a day, for the greater part of the year. Within a quarter of a mile of the great majority of farms (outside of the xx INTRODUCTION dry lands themselves) there are such streams. Only a small fraction of one per cent of them have been put to work, made to pay their passage from the hills to the sea. The United States government geological survey engineers recently made an estimate of the waterfalls capable of developing 1,000 horsepower and over, that are running to waste, unused, in this country. They esti- mated that there is available, every second of the day and night, some 30,000,000 horse- power, in dry weather and twice this during the eight wet months of the year. The water- fall capable of giving up 1,000 horsepower in energy is not the subject of these chapters. It is the small streams the brooks, the creeks, the rivulets which feed the 1,000 horsepower torrents, make them possible, that are of interest to the farmer. These small streams thread every township, every county, seeking the easiest way to the main valleys where they come together in great rivers. What profitable crop on your farm removes INTRODUCTION xxi the least plant food? A bee-farmer enters his honey for the prize in this contest. Another farmer maintains that his ice-crop is the win- ner. But electricity generated from falling water of a brook meandering across one's acres, comes nearer to the correct answer of how to make something out of nothing. It merely utilizes the wasted energy of water rolling down hill the weight of water, the pulling power of gravity. Water is still water, after it has run through a turbine wheel to turn an electric generator. It is still wet; it is there for watering the stock; and a few rods further down stream, where it drops five or ten feet again, it can be made to do the same work over again and over and over again as long as it continues to fall, on its journey to the sea. The city of Los Angeles has a municipal water plant, generating 200,000 horsepower of electricity, in which the water is used three times in its fall of 6,000 feet; and in the end, where it runs out of the race in the valley, it is sold for irrigation. One water-horsepower will furnish light xxii INTRODUCTION for the average farm; five water-horsepower will furnish light and power, and do the iron- ing and baking. The cost of installing a plant of five water-horsepower should not exceed the cost of one sound young horse, the $200 kind under conditions which are to be found on thousands of farms and farm communities in the East, the Central West, and the Pacific States. This electrical horsepower will work 24 hours a day, winter and summer, and the farmer would not have to grow oats and hay for it on land that might better be used in growing food for human beings. It would not become "aged" at the end of ten or fif- teen years, and the expense of maintenance would be practically nothing after the first cost of installation. It would require only water as food waste water. Two hundred and fifty cubic feet of water a minute, falling ten feet, will supply the average farm with all the conveniences of electricity. This is a very modest creek the kind of brook or creek that is ignored by the man who would think time well spent in putting in a* week INTRODUCTION xxiii capturing a wild horse, if a miracle should send such a beast within reach. And the task of harnessing and breaking this water- horsepower is much more simple and less dangerous than the task of breaking a colt to harness. PART I WATER-POWER ELECTRICITY FOR THE FARM CHAPTER I A WORKING PLANT The "agriculturist" An old chair factory A neigh- bor's home-coming The idle wheel hi commission again Light, heat and power for nothing Ad- vantages of electricity. LET us take an actual instance of one man who did go ahead and find out by experience just how intricate and just how simple a thing electricity from farm water-power is. This man's name was Perkins, or, we will call him that, in relating this story. Perkins was what some people call, not a farmer, but an "agriculturist,"- that is, he was a back-to-the-land man. He had been born and raised on a farm. He knew that you must harness a horse on the left side, milk a cow on the right, that wagon nuts tighten the way the wheel runs, and that a fresh egg will not float. 3 ELECTRICITY FOR THE FARM He had a farm that would grow enough clover to fill the average dairy if he fed it lime; he had a boy coming to school age; and both he and his wife wanted to get back to the country. They had their little savings, and they wanted, first of all, to take a vaca- tion, getting acquainted with their farm. They hadn't taken a vacation in fifteen years. He moved in, late in the summer, and started out to get acquainted with his neigh- bors, as well as his land. This was in the New England hills. Water courses cut through everywhere. In regard to its bountiful water supply, the neighborhood had much in com- mon with all the states east of the Mississippi, along the Atlantic seaboard, in the lake region of the central west, and in the Pacific States. With this difference; the water courses in his neighborhood had once been of economic im- portance. A mountain river flowed down his valley. Up and down the valley one met ramshackle mills, fallen into decay. Many years ago before railroads came, before it was easy to A WORKING PLANT 5 haul coal from place to place to make steam, these little mills were centers of thriving industries, which depended on the power of falling water to make turned articles, spin cotton, and so forth. Then the railroads came, and it was easy to haul coal to make steam. And the same railroads that hauled the coal to make steam, were there to haul away the articles manufactured by steam power. So in time the little manufacturing plants on the river back in the hills quit busi- ness and moved to railroad stations. Then New England, from being a manufacturing community made up of many small isolated water plants, came to be a community made up of huge arteries and laterals of smoke stacks that fringed the railroads. Where the railroad happened to follow a river course- as the Connecticut River the water-power plants remained; but the little plants back in the hills were wiped off the map because steam power with railroads at the front door proved cheaper than water-power with rail- roads ten miles away. 6 ELECTRICITY FOR THE FARM One night Perkins came in late from a long drive with his next-door neighbor. He had learned the first rule of courtesy in the coun- try, which is to unhitch his own side of the horse and help back the buggy into the shed. They stumbled around in the barn putting up the horse, and getting down hay and grain for it, by the light of an oil lantern, which was set on the floor in a place convenient to be kicked over. He went inside and took supper by the light of a smoky smelly oil lamp, that filled the room full of dark corners ; and when supper was over, the farmwife groped about in the cellar putting things away by the light of a candle. The next day his neighbor was grinding cider at his ramshackle water mill one of the operations for which a week must be set aside every fall. Perkins sat on a log and listened to the crunch-crunch of the apples in the chute, and the drip of the frothy yellow liquid that fell into waiting buckets. "How much power have you got here?" he asked. A WORKING PLANT 7 "Thirty or forty horsepower, I guess." "What do you do with it, besides grinding cider to pickle your neighbors' digestion with?" "Nothing much. I've got a planer and a moulding machine in there, to work up jags of lumber occasionally. That's all. This mill was a chair-factory in my grandfather's day, back in 1830." "Do you use it thirty days in a year? "No; not half that." "What are you going to do with it this winter?" "Nothing; I keep the gate open and the wheel turning, so it won't freeze, but nothing else. I am going to take the family to Texas to visit my wife's folks for three months. We've worked hard enough to take a vaca- tion." "Will you rent me the mill while you are gone?" "Go ahead; you can have it for nothing, if you will watch the ice." "All right; let me know when you come 8 ELECTRICITY FOR THE FARM back and I'll drive to town and bring you home." Three months went by, and one day in February the city man, in response to a letter, hitched up and drove to town to bring his neighbor back home. It was four o'clock in the afternoon when they started out, and it was six dark when they turned the bend in the road to the farm house. They helped the wife and children out, with their baggage, and as Perkins opened the door of the house, he reached up on the wall and turned some- thing that clicked sharply. Instantly light sprang from everywhere. In the barn-yard a street lamp with an 18-inch reflector illuminated all under it for a space of 100 feet with bright white rays of light. Another street lamp hung over the watering trough. The barn doors and windows burst forth in light. There was not a dark corner to be found anywhere. In the house it was the same. Perkins led the amazed procession from room to room of the house they had A WORKING PLANT 9 shut up for the winter. On the wall in the hall outside of every room was a button which he pushed, and the room became as light as day before they entered. The cellar door, in opening, automatically lighted a lamp illuminating that cavern as it had never been lighted before since the day a house was built over it. Needless to say, the farmer and his fam- ily were reduced to a state of speechless- ness. "How the deuce did you do it?" finally articulated the farmer. "I put your idle water wheel to work," said Perkins; and then, satisfied with this exhibition, he put them back in the sleigh and drove to his home, where his wife had supper waiting. While the men were putting up the team in the electric lighted barn, the farmwife went into the kitchen. Her hostess was cooking supper on an electric stove. It looked like a city gas range and it cooked all their meals, and did the baking besides. A hot- water tank 10 ELECTRICITY FOR THE FARM stood against the wall, not connected to any- thing hot, apparently. But it was scalding hot, by virtue of a little electric water heater the size of a quart tin can, connected at the bottom. Twenty-four hours a day the water wheel pumped electricity into that "can," so that hot water was to be had at any hour simply by turning a faucet. In the laundry there was an electric pump that kept the tank in the attic filled automatically. When the level of water in this tank fell to a certain point, a float operated a switch that started the pump; and when the water level reached a certain height, the same float stopped the pump. A small motor, the size of a medium Hubbard squash operated a washing machine and wringer on wash days. This same motor was a man-of-all-work for this house, for, when called on, it turned the separator, ground and polished knives and silverware, spun the sewing machine, and worked the vacuum cleaner. Over the dining room table hung the same hanging shade of old days, but the oil lamp A WORKING PLANT 11 itself was gone. In its place was a 100-watt tungsten lamp whose rays made the white table cloth fairly glisten. The wires carrying electricity to this lamp were threaded through the chains reaching to the ceiling, and one had to look twice to see where the current came from. In the sitting room, a cluster of electric bulbs glowed from a fancy wicker work basket that hung from the ceiling. The house- wife had made use of what she had through- out the house. Old-fashioned candle-shades sat like cocked hats astride electric bulbs. There is little heat to an electric bulb for the reason that the white-hot wire that gives the light is made to burn in high vacuum, which transmits heat very slowly. The house- wife had taken advantage of this fact and from every corner gleamed lights dressed in fancy designs of tissue paper and silk. "Now we will talk business," said Perkins when supper was over and they had lighted their pipes. The returned native looked dubious. His New England training had warned him long 12 ELECTRICITY FOR THE FARM ago that one cannot expect to get something for nothing, and he felt sure there was a joker in this affair. "How much do I owe you?" he asked. "Nothing," said Perkins. "You furnish the water-power with your idle wheel, and I furnish the electric installation. This is only a small plant I have put in, but it gives us enough electricity to go around, with a margin for emergencies. I have taken the liberty of wiring your house and your horse-barn and cow-barn and your barn-yard. Altogether, I suppose you have 30 lights about the place, and during these long winter days you will keep most of them going from 3 to 5 hours a night and 2 or 3 hours in the early morning. If you were in town, those lights would cost you about 12 cents an hour, at the commercial rate of electricity. Say 60 cents a day eighteen dollars a month. That isn't a very big electric light bill for some people I know in town and they consider themselves lucky to have the privilege of buying electricity at that rate. Your wheel is running all winter to A WORKING PLANT IS prevent ice from forming and smashing it. It might just as well be spinning the dynamo. "If you think it worth while," continued Perkins, "this $18 worth of light you have on tap night and morning, or any hour of the day, we will say the account is settled. That is, of course, if you will give me the use of half the electricity that your idle wheel is grinding out with my second-hand dynamo. We have about eight electrical horsepower on our wires, without overloading the machine. Next spring I am going to stock up this place; and I think about the first thing I do, when my dairy is running, will be to put in a milk- ing machine and let electricity do the milking for me. It will also fill my silo, grind my mowing-machine knives, saw my wood, and keep water running in my barn. You will probably want to do the same. "But what it does for us men in the barn and barn-yard, isn't to be compared to what it does for the women in the house. When my wife wants a hot oven she presses a button. When she wants to put the 'fire' out, she presses 14 ELECTRICITY FOR THE FARM another. That's all there is to it. No heat, no smoke, no ashes. The same with ironing and washing. No oil lamps to fill, no wicks to trim, no chimneys to wash, no kerosene to kick over and start a fire." "You say the current you have put in my house would cost me about $18 a month, in town." "Yes, about that. Making electricity from coal costs money." "What does it cost here?" "Practically nothing. Your river, that has been running to waste ever since your grand- father gave up making chairs, does the work. There is nothing about a dynamo to wear out, except the bearings, and these can be replaced once every five or ten years for a trifle. The machine needs to be oiled and cared for fill the oil cups about once in three days. Your water wheel needs the same attention. That's all there is to it. You can figure the cost of your current yourself just about the cost of the lubricating oil you use and the cost of the time you give it about the same time A WORKING PLANT 15 you give to any piece of good machinery, from a sulky plow to a cream separator." This is a true story. This electric plant, where Perkins furnishes the electric end, and his neighbor the water-power, has been running now for two years, grinding out electricity for the two places twenty-four hours a day. Perkins was not an electrical engineer. He was just a plain intelligent American citizen who found sufficient knowledge in books to enable him to install and operate this plant. Frequently he is away for long periods, but his neighbor (who has lost his original terror of electricity) takes care of the plant. In fact, this farmer has given a lot of study to the thing, through curiosity, until he knows fully as much about it now as his city neighbor. He had the usual idea, at the start, that a current strong enough to light a 100 candle- power lamp would kick like a mule if a man happened to get behind it. He watched the city man handle bare wires and finally he plucked up courage to do it himself. 16 ELECTRICITY FOR THE FARM It was a 110- volt current, the pressure used in our cities for domestic lighting. The funny part about it was, the farmer could not feel it at all at first. His fingers were calloused and no current could pass through them. Finally he sandpapered his fingers and tried it again. Then he was able to get the "tickle" of 110 volts. It wasn't so deadly after all about the strength of a weak medi- cal battery, with which every one is familiar. A current of 110 volts cannot do any harm to the human body unless contact is made over a very large surface, which is impossible unless a man goes to a lot of trouble to make such a contact. A current of 220 volts pres- sure the pressure used in cities for motors- has a little more "kick" to it, but still is not uncomfortable. When the pressure rises to 500 volts (the pressure used in trolley wires for street cars), it begins to be dangerous. But there is no reason why a farm plant should be over 110 volts, under usual conditions; engineers have decided on this pressure as the best adapted to domestic use, and manu- A WORKING PLANT 17 facturers who turn out the numerous electri- cal devices, such as irons, toasters, massage machines, etc., fit their standard instruments to this voltage. As to the cost of this co-operative plant it was in the neighborhood of $200. As we have said, it provided eight electrical horse- power on tap at any hour of the day or night enough for the two farms, and a surplus for neighbors, if they wished to string lines and make use of it. The dynamo, a direct-current machine, 110 volts pressure, and what is known in the trade as "compound,"- that is, a machine that maintains a constant pressure auto- matically and does not require an attendant was picked up second-hand, through a news- paper "ad" and cost $90. The switchboard, a make-shift affair, not very handsome, but just as serviceable as if it were made of mar- ble, cost less than $25 all told. The trans- mission wire cost $19 a hundred pounds; it is of copper, and covered with weatherproofed tape. Perkins bought a 50-cent book on 18 ELECTRICITY FOR THE FARM house-wiring, and did the wiring himself, the way the book told him to, a simple opera- tion. For fixtures, as we have said, his wife devised fancy shades out of Mexican baskets, tissue paper, and silk, in which are hidden electric globes that glow like fire-flies at the pressing of a button. The lamps themselves are mostly old-style carbon lamps, which can be bought at 16 cents each retail. In his living room and dining room he used the new- style tungsten lamps instead of old-style carbon. These cost 30 cents each. Incandes- cent lamps are rated for 1,000 hours useful life. The advantage of tungsten lights is that they give three times as much light for the same expenditure of current as carbon lights. This is a big advantage in the city, where current is costly; but it is not so much of an advantage in the country where a farmer has plenty of water-power because his cur- rent costs him practically nothing, and he can afford to be wasteful of it to save money in lamps. Another advantage he has over his city cousin: In town, an incandescent lamp is A WORKING PLANT 19 thrown away after it has been used 1,000 hours because after that it gives only 80% of the light it did when new quite an item when one is paying for current. The experience of Perkins and his neighbor in their coopera- tive plant has been that they have excess light anyway, and if a few bulbs fall off a fifth in efficiency, it is not noticeable. As a matter of fact most of their bulbs have been in use without replacing for the two years the plant has been in operation. The lamps are on the wall or the ceiling, out of the way, not liable to be broken; so the actual expense in replacing lamps is less than for lamp chim- neys in the old days. Insurance companies recognize that a large percentage of farm fires comes from the use of kerosene; for this reason, they are willing to make special rates for farm homes lighted by electricity. They prescribe certain rules for wiring a house, and they insist that their agent inspect and pass such wiring before current is turned on. Once the wiring is passed, the advantage is all in favor of the 20 ELECTRICITY FOR THE FARM farmer with electricity over the farmer with kerosene. The National Board of Fire Under- writers is sufficiently logical in its demands, and powerful enough, so that manufacturers who turn out the necessary fittings find no sale for devices that do not conform to insur- ance standards. Therefore it is difficult to go wrong in wiring a house. Finally, as to the added value a water- power electric plant adds to the selling price of a farm. Let the farmer answer this ques- tion for himself. If he can advertise his farm for sale, with a paragraph running: "Hydro- electric plant on the premises, furnishing electricity for light, heat, and power" what do you suppose a wide-awake purchaser would be willing to pay for that? Perkins and his neighbor believe that $1,000 is a very modest estimate added by their electric plant to both places. And they talk of doing still more. They use only a quarter of the power of the water that is running to waste through the wheel. They are figuring on installing a larger dynamo, of say 30 electrical horse- A WORKING PLANT 21 power, which will provide clean, dry, safe heat for their houses even on the coldest days in winter. When they have done this, they will consider that they are really putting their small river to work. CHAPTER II A LITTLE PROSPECTING Small amount of water required for an electric plant Exploring, on a dull day A rough and ready weir What a little water will do The water wheel and the dynamo Electricity consumed the instant it is produced The price of the aver- age small plant, not counting labor. THE average farmer makes the mistake of considering that one must have a river of some size to develop power of any practical use. On your next free day do a little pros- pecting. We have already said that 250 cubic feet of water falling 10 feet a minute will provide light, heat and small motor power for the average farm. A single water horsepower will generate enough electricity to provide light for the house and barn. But let us take five horsepower as a desirable minimum in this instance. In your neighborhood there is a creek three sc c c A LITTLE PROSPECTING 23 or four feet wide, toiling along day by day, at its task of watering your fields. Find a wide board a little longer than the width of this creek you have scorned. Set it upright across the stream between the banks, so that no water flows around the ends or under it. It should be high enough to set the water back to a dead level for a few feet upstream, before it overflows. Cut a gate in this board, say three feet wide and ten inches deep, or according to the size of a stream. Cut this gate from the top, so that all the water of the stream will flow through the opening, and still maintain a level for several feet back of the board. This is what engineers call a weir, a handy contrivance for measuring the flow of small streams. Experts have figured out an elabo- rate system of tables as to weirs. All we need to do now, in this rough survey, is to figure out the number of square inches of water flowing through this opening and falling on the other side. With a rule, measure the depth of the overflowing water, from the bot- 24 ELECTRICITY FOR THE FARM torn of the opening to the top of the dead level of the water behind the board. Mul- tiply this depth by the width of the opening, which will give the square inches of water escaping. For every square inch of this water escaping, engineers tell us that stream is capable of delivering, roughly, one cubic foot of water a minute. Thus, if the water is 8 inches deep in an opening 32 inches wide, then the number of cubic feet this stream is delivering each min- ute is 8 times 32, or 256 cubic feet a minute. So, a stream 32 inches wide, with a uniform depth of 8 inches running through our weir is capable of supplying the demands of the average farm in terms of electricity. Pro- viding, of course, that the lay of the land is such that this water can be made to fall 10 feet into a water wheel. Go upstream and make a rough survey of the fall. In the majority of instances (unless this is some sluggish stream in a flat prairie) it will be found feasible to divert the stream from its main channel by means of a race an A LITTLE PROSPECTING 25 artificial channel and to convey it to a not far-distant spot where the necessary fall can be had at an angle of about 30 degrees from horizontal. If you find there is twice as much water as you need for the amount of power you require, a five-foot fall will give the same result. Or, if there is only one-half as much water as the 250 cubic feet specified, you can still obtain your theoretical five horsepower if the means are at hand for providing a fall of twenty feet in- stead of ten. Do not make the very common mistake of figuring that a stream is delivering a cubic foot a minute to each square inch of weir opening, simply because it fills a certain opening. It is the excess water, falling over the opening, after the stream has set back to a permanent dead level, that is to be measured. This farmer who spends an idle day meas- uring the flow of his brook with a notched board, may say here: "This is all very well. This is the spring of the year, when my brook is flowing at high-water mark. What am I going to do in the dry months of summer, when 26 ELECTRICITY FOR THE FARM there are not 250 cubic feet of water escaping every minute?" There are several answers to this question, which will be taken up in detail in subsequent chapters. Here, let us say, even if this brook does flow in sufficient volume only 8 months in a year the dark months, by the way, is not electricity and the many benefits it pro- vides worth having eight months in the year? My garden provides fresh vegetables four months a year. Because it withers and dies and lies covered with snow during the winter, is that any reason why I should not plow and manure and plant my garden when spring comes again? A water wheel, the modern turbine, is a circular fan with curved iron blades, revolving in an iron case. Water, forced through the blades of this fan by its own weight, causes the wheel to revolve on its axis; and the fan, in turn causes a shaft fitted with pulleys to re- volve. The water, by giving the iron-bladed fan a turning movement as it rushes through, im- A LITTLE PROSPECTING 27 parts to it mechanical power. The shaft set in motion by means of this mechanical power is, in turn, belted to the pulley of a dynamo. This dynamo consists, first, of a shaft on which is placed a spool, wound in a curious way, with many turns of insulated copper wire. This spool revolves freely in an air space surrounded by electric magnets. The spool does not touch these magnets. It is so nicely balanced that the weight of a finger will turn it. Yet, when it is revolved by water-power at a predetermined speed say 1,500 revolutions a minute it generates electricity, transforms the mechanical power of the water wheel into another form of en- ergy a form of energy which can be carried for long distances on copper wires, which can, by touching a button, be itself converted into light, or heat, or back into mechanical energy again. If two wires be led from opposite sides of this revolving spool, and an electric lamp be connected from one to the other wire, the lamp will be lighted will grow white hot, 28 ELECTRICITY FOR THE FARM hence incandescent light. The instant this lamp is turned on, the revolving spool feels a stress, the magnets by which it is surrounded begin to pull back on it. The power of the water wheel, however, overcomes this pull. If one hundred lights be turned on, the back- ward pull of the magnets surrounding the spool will be one hundred times as strong as for one light. For every ounce of electrical energy used in light or heat or power, the dynamo will require a like ounce of me- chanical power from the water wheel which drives it. The story is told of a canny Scotch engineer, who, in the first days of dynamos, not so very long ago, scoffed at the suggestion that such a spool, spinning in free air, in well lubricated bearings, could bring his big Corliss steam engine to a stop. Yet he saw it done simply by belting this "spool," a dynamo, to his engine and asking the dynamo for more power in terms of light than his steam could deliver in terms of mechanical power to overcome the pull of the magnets. A LITTLE PROSPECTING 29 Electricity must be consumed the instant it is generated (except in rare instances where small amounts are accumulated in storage batteries by a chemical process) . The pressure of a button, or the throw of a switch causes the dynamo instantly to respond with just enough energy to do the work asked of it, always in proportion to the amount required. Having this in mind, it is rather curious to think of electricity as being an article of export, an item in international trade. Yet in 1913 hydro-electric companies in Canada "ex- ported" by means of wires, to this country over 772,000,000 kilowatt-hours (over one billion horsepower hours) of electricity for use in factories near the boundary line. This 250 cubic feet of water per minute then, which the farmer has measured by means of his notched board, will transform by means of its falling weight mechanical power into a like amount of electrical power less friction losses, which may amount to as much as 60% in very small machines, and 15% in larger SO ELECTRICITY FOR THE FARM plants. That is, the brook which has been draining your pastures for uncounted ages contains the potential power of 3 and 4 young horses with this difference: that it works 24 hours a day, runs on forever, and requires no oats or hay. And the cost of such an electric plant, which is ample for the needs of the average farm, is in most cases less than the price of a good farm horse the $200 kind not counting labor of installation. It is the purpose of these chapters to awaken the farmer to the possibilities of such small water-power as he or his community may possess; to show that the generating of elec- tricity is a very simple operation, and that the maintenance and care of such a plant is within the mechanical ability of any American farmer or farm boy; and to show that elec- tricity itself is far from being the dangerous death-dealing "fluid" of popular imagination. Electricity must be studied; and then it becomes an obedient, tireless servant. During the past decade or two, mathematical wizards have studied electricity, explored its atoms, A LITTLE PROSPECTING 31 reduced it to simple arithmetic and although they cannot yet tell us why it is generated, they tell us how. It is with this simple arith- metic, and the necessary manual operations that we have to do here. CHAPTER III HOW TO MEASURE WATER-POWER What is a horsepower? How the Carthaginians manu- factured horsepower All that goes up must come down How the sun lifts water up for us to use Water the ideal power for generating electricity The weir Table for estimating flow of streams, with a weir Another method of measuring Figuring water horsepower The size of the wheel What head is required Quantity of water necessary. IF a man were off in the woods and needed a horsepower of energy to work for him, he could generate it by lifting 550 pounds of stone or wood, or whatnot, one foot off the ground, and letting it fall back in the space of one second. As a man possesses capacity for work equal to one-fifth horsepower, it would take him five seconds to do the work of lifting the weight up that the weight itself accom- plished in falling down. All that goes up must come down; and by a nice balance of 32 HOW TO MEASUKE WATER-POWER 33 physical laws, a falling body hits the ground with precisely the same force as is re- quired to lift it to the height from which it falls. The Carthaginians, and other ancients (who were deep in the woods as regards mechanical knowledge) had their slaves carry huge stones to the top of the city wall; and the stones were placed in convenient positions to be tipped over on the heads of any besieging army that happened along. Thus by concentrating the energy of many slaves in one batch of stones, the warriors of that day were enabled to de- liver "horsepower" in one mass where it would do the most good. The farmer who makes use of the energy of falling water to generate electricity for light, heat, and power does the same thing he makes use of the capacity for work stored in water in being lifted to a certain height. As in the case of the gasoline engine, which burns 14 pounds of air for every pound of gasoline, the engineer of the water-power plant does not have to concern himself with the question of how this 34 ELECTRICITY FOR THE FARM natural source of energy happened to be in a handy place for him to make use of it. The sun, shining on the ocean, and turning water into vapor by its heat has already lifted it up for him. This vapor floating in the air and blown about by winds, becomes chilled from one cause or another, gives up its heat, turns back into water, and falls as rain. This rain, falling on land five, ten, a hundred, a thousand, or ten thousand feet above the sea level, begins to run back to the sea, picking out the easiest road and cutting a channel that we call a brook, a stream, or a river. Our farm lands are covered to an average depth of about three feet a year with water, every gallon of which has stored in it the energy expended by the heat of the sun in lifting it to the height where it is found. The farmer, prospecting on his land for water-power, locates a spot on a stream which he calls Supply; and another spot a few feet down hill near the same stream, which he calls Power. Every gallon of water that falls between these two points, and is made to HOW TO MEASURE WATER-POWER 35 escape through the revolving blades of a water wheel is capable of work in terms of foot-pounds an amount of work that is directly proportional to the quantity of water, and to the distance in feet which it falls to reach the wheel pounds smdfeet. The Efficient Water Wheel And it is a very efficient form of work, too. In fact it is one of the most efficient forms of mechanical energy known and one of the easiest controlled. A modern water wheel uses 85 per cent of the total capacity for work imparted to falling water by gravity, and delivers it as rotary motion. Compare this water wheel efficiency with other forms of mechanical power in common use: Whereas a water wheel uses 85 per cent of the energy of its water supply, and wastes only 15 per cent, a gasoline engine reverses the table, and delivers only 15 per cent of the energy in gasoline and wastes 85 per cent and it is rather a high-class gasoline engine that can deliver even 15 per cent; a steam engine, on 36 ELECTRICITY FOR THE FARM the other hand, uses about 17 per cent of the energy in the coal under its boilers and passes the rest up the chimney as waste heat and smoke. There is still another advantage possessed by water-power over its two rivals, steam and gas: It gives the most even flow of power. A gas engine "kicks" a wheel round in a circle, by means of successive explosions in its cylinders. A reciprocating steam engine "kicks" a wheel round in a circle by means of steam expanding first in one direction, then in another. A water wheel, on the other hand, is made to revolve by means of the pressure of water by the constant force of gravity, itself weight. Weight is something that does not vary from minute to minute, or from one fraction of a second to another. It is always the same. A square inch of water pressing on the blades of a water wheel weights ten, twenty, a hundred pounds, according to the height of the pipe conveying that water from the source of supply, to the wheel. So long as this column of water is HOW TO MEASURE WATER-POWER 37 maintained at a fixed height, the power it delivers to the wheel does not vary by so much as the weight of a feather. This property of falling water makes it the ideal power for generating electricity. Elec- tricity generated from mechanical power de- pends on constant speed for steady pressure since the electric current, when analyzed, is merely a succession of pulsations through a wire, like waves beating against a sea wall. Water-power delivers these waves at a con- stant speed, so that electric lights made from water-power do not flicker and jump like the flame of a lantern in a gusty wind. On the other hand, to accomplish the same thing with steam or gasoline requires an especially con- structed engine. The Simple Weir Since a steady flow of water, and a constant head, bring about this ideal condition in the water wheel, the first problem that faces the farmer prospector is to determine the amount of water which his stream is capable of de- 38 ELECTRICITY FOR THE FARM livering. This is always measured, for con- venience, in cubic feet per minute. (A cubic foot of water weighs 62.5 pounds, and con- tains 7% gallons.) This measurement is ob- tained in several ways, among which prob- ably the use of a weir is the simplest and most accurate, for small streams. A weir is, in effect, merely a temporary dam set across the stream in such a manner as to form a small pond; and to enable one to measure the water escaping from this pond. It may be likened to the overflow pipe of a horse trough which is being fed from a spring. Tomeas- Detail of home-made weir ure jj^ fJ QW Q f water from such a spring, all that is necessary is to measure the water escaping through the overflow when the water in the trough has attained a permanent level. The diagrams show the cross-section and detail of a typical weir, which can be put HOW TO MEASURE WATER-POWER 39 together in a few minutes with the aid of a saw and hammer. The cross-section shows that the lower edge of the slot through which the water of the temporary pond is made to escape, is cut on a bevel, with its sharp edge upstream. The wing on each side of the opening is for the purpose of preventing the stream from narrowing as it flows through the opening, and thus upsetting the calculations. This weir should be set directly across the flow of the stream, perfectly level, and upright. It should be so im- bedded in the banks, and in the bottom of the stream, that no water can escape, except through the opening cut for that purpose. It will require a little experi- menting with a rough model to determine just how wide and how deep this opening should be. It should be large enough to prevent water flowing over the top of the Cross-section of weir 40 ELECTRICITY FOR THE FARM board; and it should be small enough to cause a still-water pond to form for several feet behind the weir. Keep in mind the idea of the overflowing water trough when building your weir. The stream, running down from a higher level behind, should be emptying into a still- water pond, which in turn should be emptying itself through the aperture in the board at the same rate as the stream is keeping the pond full. Your weir should be fashioned with the idea of some permanency so that a number of measurements may be taken, extending over a period of time thus enabling the prospector to make a reliable estimate not only of the amount of water flowing at any one time, but of its fluctuations. Under expert supervision, this simple weir is an exact contrivance exact enough, in fact, for the finest calculations required in engineer- ing work. To find out how many cubic feet of water the stream is delivering at any moment, all that is necessary is to measure its depth where it flows through the opening. There are HOW TO MEASURE WATER-POWER 41 instruments, like the hook-gauge, which are designed to measure this depth with accuracy up to one-thousandth of an inch. An ordinary foot rule, or a folding rule, will give results sufficiently accurate for the water prospector in this instance. The depth should be meas- ured not at the opening itself, but a short distance back of the opening, where the water is setting at a dead level and is moving very slowly. With this weir, every square inch of water flowing through the opening indicates roughly one cubic foot of water a minute. Thus if the opening is 10 inches wide and the water flow- ing through it is 5 inches deep, the number of cubic feet a minute the stream is delivering is 10 x 5 = 50 square inches = 50 cubic feet a minute. This is a very small stream; yet, if it could be made to fall through a water wheel 10 feet below a pond or reser- voir, it would exert a continuous pressure of 30,000 pounds per minute on the blades of the wheel nearly one theoretical horse- power. 42 ELECTRICITY FOR THE FARM This estimate of one cubic foot to each square inch is a very rough approximation. Engineers have developed many complicated formulas for determining the flow of water through weirs, taking into account fine varia- tions that the farm prospector need not heed. The so-called Francis formula, developed by a long series of actual experiments at Lowell, Mass., in 1852 by Mr. James B. Francis, with weirs 10 feet long and 5 feet 2 inches high, is standard for these calculations and is expressed (for those who desire to use it for special purposes) as follows : Q = 3.33 L H or, Q = 3.33 L in which Q means quantity of water in cubic feet per second, L is length of open- ing, in feet; and H is height of opening in feet. The following table is figured according to the Francis formula, and gives the discharge in cubic feet per minute, for openings one inch wide: HOW TO MEASURE WATER-POWER 43 TABLE OF WEIRS Inchet 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Thus, let us say, our weir has an opening 30 inches wide, and the water overflows through the opening at a uniform depth of 6j^ inches, when measured a few inches be- hind the board at a point before the overflow curve begins. Run down the first column on the left to "6", and cross over to the second column to the right, headed "34"- This gives the number of cubic feet per min- ute for this depth one inch wide, as 6.298. M ^ M 0.403 0.563 0.740 0.966 1.141 1.360 1.593 1.838 2.094 2.361 2.639 2.927 3.225 3.531 3.848 4.173 4.506 4.849 5.200 5.558 5.925 6.298 6.681 7.071 7.465 7.869 8.280 8.697 9.121 9.552 9.990 10.427 10.884 11.340 11.804 12.272 12.747 13.228 13.716 14.208 14.707 15.211 15.721 16.236 16.757 17.283 17.816 18.352 18.895 19.445 19.996 20.558 21.116 21.684 22.258 22.835 23.418 24.007 24.600 25.195 25.800 26.406 27.019 27.634 28.256 28.881 29.512 30.145 30.785 31.429 32.075 32.733 44 ELECTRICITY FOR THE FARM Since the weir is 30 inches wide, multiply 6.298 x 30 = 188.94 or, say, 189 cubic feet per minute. Once the weir is set, it is the work of but a moment to find out the quantity of water a stream is delivering, simply by referring to the above table. Another Method of Measuring a Stream Weirs are for use in small streams. For larger streams, where the construction of a weir would be difficult, the U. S. Geological Survey engineers recommend the following simple method : Choose a place where the channel is straight for 100 or 200 feet, and has a nearly constant depth and width; lay off on the bank a line 50 or 100 feet in length. Throw small chips into the stream, and measure the time in seconds they take to travel the distance laid off on the bank. This gives the surface velocity of the water. Multiply the average of several such tests by 0.80, which will give very nearly the mean velocity. Then it is HOW TO MEASURE WATER-POWER 45 necessary to find the cross-section of the flowing water (its average depth multiplied by width), and this number, in square feet, multiplied by the velocity in feet per second, will give the number of cubic feet the stream is delivering each second. Multiplied by 60 gives cubic feet a minute. Figuring a Stream 9 s Horsepower By one of the above simple methods, the problem of Quantity can easily be determined. The next problem is to determine what Head can be obtained. Head is the distance in feet the water may be made to fall, from the Source of Supply, to the water wheel itself. The power of water is directly proportional to head, just as it is directly proportional to quantity. Thus the typical weir measured above was 30 inches wide and 6j^ deep, giving 189 cubic feet of water a minute Quantity. Since such a stream is of common occurrence on thousands of farms, let us an- alyze briefly its possibilities for power: One hundred and eighty-nine cubic feet of water 46 ELECTRICITY FOR THE FARM II r r i ^ ~*M i%|^ 2kj / feM X ly 1 /' ili 1 HOW TO MEASURE WATER-POWER 47 weighs 189 x 62.5 pounds = 11,812.5 pounds. Drop this weight one foot, and we have 11,812.5 foot-pounds. Drop it 3 feet and we have 11,812 x 3 = 35,437.5 foot-pounds. Since 33,000 foot-pounds exerted in one minute is one horsepower, we have here a little more than one horsepower. For simplic- ity let us call it a horsepower. Now, since the work to be had from this water varies directly with quantity and head, it is obvious that a stream one-half as big falling twice as far, would still give one horse- power at the wheel; or, a stream of 189 cubic feet a minute falling ten times as far, 30 feet, would give ten times the power, or ten horse- power; a stream falling one hundred times as far would give one hundred horsepower. Thus small quantities of water falling great distances, or large quantities of water falling small distances may accomplish the same results. From this it will be seen, that the simple formula for determining the theoreti- cal horsepower of any stream, in which Quan- tity and Head are known, is as follows: 48 ELECTRICITY FOR THE FARM Cu. Ft. per Feet _. minute x head x 62.5 (A) Theoretical Horsepower = 33,000 As an example, let us say that we have a stream whose weir measurement shows it capable of delivering 376 cubic feet a minute, with a head (determined by survey) of 13 feet 6 inches. What is the horsepower of this stream? Cu. ft. p. m. head pounds Answer: 376 x 13 - 5 x 62 - 5 TT p ' = =9. 6 14 horsepower H - ^ 33,000 This is theoretical horsepower. To determine the actual horsepower that can be counted on, in practice, it is customary, with small water wheels, to figure 25 per cent loss through friction, etc. In this instance, the actual horsepower would then be 7.2. The Size of the Wheel Water wheels are not rated by horsepower by manufacturers, because the same wheel might develop one horsepower or one hundred horsepower, or even a thousand horsepower, HOW TO MEASURE WATER-POWER 49 according to the conditions under which it is used. With a given supply of water, the head, in feet, determines the size of wheel necessary. The farther a stream of water falls, the smaller the pipe necessary to carry a given number of gallons past a given point in a given time. A small wheel, under 10 x 13.5 ft. head, would give the same power with the above 376 cubic feet of water a minute, as a large wheel would with 10 x 376 cubic feet, under a 13.5 foot head. This is due to the acceleration of gravity on falling bodies. A rifle bullet shot into the air with a muzzle velocity of 3,000 feet a second begins to diminish its speed instantly on leaving the muzzle, and continues to dim- inish in speed at the fixed rate of 32.16 feet a second, until it finally comes to a stop, and starts to descend. Then, again, its speed accelerates at the rate of 32.16 feet a second, until on striking the earth it has attained the velocity at which it left the muzzle of the rifle, less loss due to friction. 50 ELECTRICITY FOR THE FARM The acceleration of gravity affects falling water in the same manner as it affects a falling bullet. At any one second, during its course of fall, it is traveling at a rate 32.16 feet a second in excess of its speed the previous second. In figuring the size wheel necessary under given conditions or to determine the power of water with a given nozzle opening, it is necessary to take this into account. The table on page 51 gives velocity per second of falling water, ignoring the friction of the pipe, in heads from 5 to 1000 feet. The scientific formula from which the table is computed is expressed as follows, for those of a mathematical turn of mind: Velocity (ft. per sec.) = ^2gh; or, veloc- ity is equal to the square root of the product (g = 32.16, times head in feet, multiplied by 2). In the above example, we found that 376 cubic feet of water a minute, under 13.5 feet head, would deliver 7.2 actual horsepower. Question: HOW TO MEASURE WATER-POWER 51 SPOUTING VELOCITY OF WATER, IN FEET PER SECOND, IN HEADS OF FROM 5 TO 1,000 FEET Head Velodt, 5 17.9 6 19.7 7 21.2 8 22.7 9 24.1 10 25.4 11 26.6 11.5 27.2 12 27.8 12.5 28.4 13 28.9 13.5 29.5 14 30.0 14.5 30.5 15 31.3 15.5 31.6 16 32.1 16.5 32.6 17 33.1 17 . 5 33 . 6 18 34.0 18.5 34.5 19 35.0 19.5 35.4 20 35.9 20.5 36.3 21 36.8 21.5 37.2 22 37.6 22.5 38.1 23 38.5 23.5 38.9 24 39.3 24.5 39.7 25 - 40.1 26 40.9 27 41.7 28.. . 42.5 Head Velocity 29 43.2 30 43.9 31 44.7 32 45.4 33 46.1 34 46.7 35 47.4 36 48.1 37 48.8 38 49.5 39 50.1 40 50.7 41 51.3 42 52.0 43 52.6 44 53.2 45 53.8 46 54.4 47 55.0 48 55.6 49 56 2 50 56.7 55 59.5 60 62.1 65 64.7 70 67.1 75 69.5 80 71.8 85 74.0 90 76.1 95 78.2 100 80.3 200 114.0 300 139.0 400 160.0 500 179.0 1000 254.0 52 ELECTRICITY FOR THE FARM What size wheel would it be necessary to install under such conditions? By referring to the table of velocity above, (or by using the formula), we find that water under a head of 13.5 feet, has a spouting veloc- ity of 29.5 feet a second. This means that a solid stream of water 29.5 feet long would pass through the wheel in one second. What should be the diameter of such a stream, to make its cubical contents 376 cubic feet a minute or f| = 6.27 cubic feet a second? The following formula should be used to determine this: /T>\ o T t s i. i 144 x cu. ft. per second (B) Sq. Inches of wheel = ^-, ^7 ; -- Velocity in ft. per sec. Substituting values, in the above instance, we have: Answer: Sq. Inches of wheel = 144 x 6.27 (Cu. Ft. Sec.) _ 30 6 SQ in 29.5 (Vel. in feet.) That is, a wheel capable of using 30.6 square inches of water would meet these conditions. HOW TO MEASURE WATER-POWER 53 What Head is Required Let us attack the problem of water-power in another way. A farmer wishes to install a water wheel that will deliver 10 horsepower on the shaft, and he finds his stream delivers 400 cubic feet of water a minute. How many feet fall is required? Formula : (C) Head in feet = 33,000 x horsepower required Cu. Ft. per minute x 62.5 Since a theoretical horsepower is only 75 per cent efficient, he would require 10 x j = 13.33 theoretical horsepower of water, in this instance. Substituting the values of the problem in the formula, we have: A , 33,000 x 13.33 ,_.,, . , Answer: Head = 77:7: ^TTT~ =17.6 feet fall required. 400 x 62.5 What capacity of wheel would this prospect (400 cubic feet of water a minute falling 17.6 feet, and developing 13.33 horsepower) require? By referring to the table of velocities, we find that the velocity for 17.5 feet head (nearly) is 33.6 feet a second. Four hundred 54 ELECTRICITY FOR THE FARM feet of water a minute is f^ = 6.67 cu. ft. a second. Substituting these values, in formula (B) then, we have: Answer: Capacity of wheel = 144 x 6.67 . , , ==-= = 28.6 square inches of water. ' OO.D Quantity of Water Let us take still another problem which the prospector may be called on to solve: A man finds that he can conveniently get a fall of 27 feet. He desires 20 actual horsepower. What quantity of water will be necessary, and what capacity wheel? Twenty actual horsepower will be 20 x | = 26.67 theoretical horsepower. Formula: 33,000 x Hp. required (D) Cubic feet per minute = H ead in feet x 62.5 Substituting values, then, we have: Cu. ft. per minute = 3 % 7 x X 6 f 5 67 = 521.5 cubic feet a minute. A head of 27 feet would give this stream a velocity of 41.7 feet a second, and, from HOW TO MEASURE WATER-POWER 55 formula (B) we find that the capacity of the wheel should be 30 square inches. It is well to remember that the square inches of wheel capacity does not refer to the size of pipe conveying water from the head to the wheel, but merely to the actual nozzle capacity provided by the wheel itself. In small installations of low head, such as above a penstock at least six times the nozzle capac- ity should be used, to avoid losing effective head from friction. Thus, with a nozzle of 30 square inches, the penstock or pipe should be 180 square inches, or nearly 14 inches square inside measurement. A larger penstock would be still better. CHAPTER IV THE WATER WHEEL AND HOW TO INSTALL IT Different types of water wheels The impulse and reaction wheels The impulse wheel adapted to high heads and small amount of water Pipe lines Table of resistance in pipes Advantages and disadvantages of the impulse wheel Other forms of impulse wheels The reaction turbine, suited to low heads and large quantity of water Its advantages and limitations Developing a water-power project: the dam; the race; the flume; the penstock; and the tailrace Water rights for the farmer. IN general, there are two types of water wheels, the impulse wheel and the reaction wheel. Both are called turbines, although the name belongs, more properly, to the reaction wheel alone. Impulse wheels derive their power from the momentum of falling water. Reaction wheels derive their power from the momentum and pressure of falling water. The old- fashioned undershot, overshot, and breast wheels 56 WATER WHEEL, HOW TO INSTALL IT 57 are familiar to all as examples of impulse wheels. Water wheels of this class revolve in the air, with the energy of the water exerted on one face of their buckets. On the other hand, reaction wheels are enclosed in water- tight cases, either of metal or of wood, and the buckets are entirely surrounded by water. The old-fashioned undershot, overshot, and breast wheels were not very efficient; they wasted about 75 per cent of the power ap- plied to them. A modern impulse wheel, on the other hand, operates at an efficiency of 80 per cent and over. The loss is mainly through friction and leakage, and cannot be eliminated altogether. The modern reaction wheel, called the turbine, attains an equal efficiency. Individual conditions govern the type of wheel to be selected. The Impulse, or Tangential Water Wheel The modern impulse, or tangential wheel (so called because the driving stream of water strikes the wheel at a tangent) is best adapted to situations where the amount of water is 58 ELECTRICITY FOR THE FARM limited, and the head is large. Thus, a moun- tain brook supplying only seven cubic feet of water a minute a stream less than two- and-a-half inches deep flowing over a weir with an opening three inches wide would develop two actual horsepower, under a head of 200 feet not an unusual head to be found in the hill country. Under a head of one thousand feet, a stream furnishing 352.6 cubic feet of water a minute would develop 534.01 horse- power at the nozzle. Ordinarily these wheels are not used under heads of less than 20 feet. A wheel of this type, six feet in diameter, would develop six horsepower, with 188 cubic feet of water a minute and 20-foot head. The great majority of impulse wheels are used under heads of 100 feet and over. In this country the greatest head in use is slightly over 2,100 feet, although in Switzerland there is one plant utilizing a head of over 5,000 feet. The old-fashioned impulse wheels were inefficient because of the fact that their buckets were not constructed scientifically, Runner of Pelton wheel, showing peculiar shape of the buckets The Fitz overshoot wheel EFFICIENT MODERN ADAPTATIONS OF THE ARCHAIC UNDERSHOT AND OVERSHOT WATER WHEEUS WATER WHEEL, HOW TO INSTALL IT 59 and much of the force of the water was lost at the moment of impact. . The impulse wheel of to-day, however, has buckets which so com- pletely absorb the momentum of water issuing from a nozzle, that the water falls into the tailrace with practically no velocity. When it is remembered that the nozzle pressure under a 2,250-foot head is nearly 1,000 pounds to the square inch, and that water issues from this nozzle with a velocity of 23,000 feet a minute, the scientific precision of this type of bucket can be appreciated. A typical bucket for such a wheel is shaped like an open clam shell, the central line which cuts the stream of water into halves being ground to a sharp edge. The curves which absorb the momentum of the water are figured mathematically and in practice become polished like mirrors. So great is the eroding action of water, under great heads especially when it contains sand or silt that it is occa- sionally necessary to replace these buckets. For this reason the larger wheels consist merely of a spider of iron or steel, with each 60 ELECTRICITY FOR THE FARM bucket bolted separately to its circumference, so that it can be removed and replaced easily. Usually only one nozzle is provided; but in order to use this wheel under low heads down to 10 feet a number of nozzles are used, sometimes five, where the water supply is plentiful. The wheel is keyed to a horizontal shaft running in babbited bearings, and this same shaft is used for driving the generator, either by direct connection, or by means of pulleys and a belt. The wheel may be mounted on a home-made timber base, or on an iron frame. It takes up very little room, especially when it is so set that the nozzle can be mounted under the flooring. The wheel itself is en- closed, above the floor, in a wooden box, or a casing made of cast or sheet iron, which should be water-tight. Since these wheels are usually operated under great heads, the problem of regulating their water supply requires special considera- tion. A gate is always provided at the upper, or intake end, where the water pipe leaves the WATER WHEEL, HOW TO INSTALL IT 61 flume. Since the pressure reaches 1,000 pounds the square inch and more, there would be danger of bursting the pipe if the water were suddenly shut off at the nozzle itself. For this reason it is necessary to use a needle valve, similar to that in an ordinary garden hose nozzle; and by such a valve the amount of water may be regulated to a nicety. Where the head is so great that even such a valve could not be used safely, provision is made to deflect the nozzle. These wheels have a speed variation amounting to as much as 25 per cent from no-load to full load, in gen- erating electricity, and since the speed of the prime mover the water wheel is reflected directly in the voltage or pressure of electricity delivered, the wheel must be provided with some form of automatic governor. This con- sists usually of two centrifugal balls, similar to those used in governing steam engines; these are connected by means of gears to the needle valve or the deflector. As the demand for farm water-powers in our hill sections becomes more general, the 62 ELECTRICITY FOR THE FARM tangential type of water wheel will come into common use for small plants. At present it is most familiar in the great commercial in- stallations of the Far West, working under enormous heads. These wheels are to be had in the market ranging in size from six inches to six feet and over. Wheels ranging in size from six inches to twenty-four inches are called water motors, and are to be had in the market, new, for $30 for the smallest size, and $275 for the largest. Above three feet in diameter, the list prices will run from $200 for a 3 -foot wheel to $800 for a 6 -foot wheel. Where one has a surplus of water, it is possible to install a multiple nozzle wheel, under heads of from 10 to 100 feet, the cost for 18-inch wheels of this pattern running from $150 to $180 list, and for 24-inch wheels from $200 to $250. A 24-inch wheel, with a 10-foot head would give 1.19 horsepower, enough for lighting the home, and using an electric iron. Under a 100-foot head this same wheel would provide 25.9 horsepower, to meet the requirements of a bigger-than-average farm plant. WATER WHEEL, HOW TO INSTALL IT 63 The Pipe Line The principal items of cost in installing an impulse wheel are in connection with the pipe line, and the governor. In small heads, that is, under 100 feet, the expense of pipe line is low. Frequently, however, the governor will cost more than the water motor itself, although cheaper, yet efficient, makes are now being put on the market to meet this objection. In a later chapter, we will take up in detail the question of governing the water wheel, and voltage regulation, and will attempt to show how this expense may be practically eliminated by the farmer. To secure large heads, it is usually necessary to run a pipe line many hundreds (and in many cases, many thousands) of feet from the flume to the water wheel. Water flowing through pipes is subject to loss of head, by friction, and for this reason the larger the pipe the less the friction loss. Under no circumstances is it recommended to use a pipe of less than two inches in diameter, even for the smallest water 64 ELECTRICITY FOR THE FARM motors; and with a two-inch pipe, the run should not exceed 200 feet. Where heavy- pressure mains, such as those of municipal or commercial water systems, are available, the problem of both water supply and head becomes very simple. Merely ascertain the pressure of the water in the mains when flowing, determine the amount of power required (as illustrated in a succeeding chapter of this book), and install the proper water motor with a suitably sized pipe. Where one has his own water supply, how- ever, and it is necessary to lay pipe to secure the requisite fall, the problem is more difficult. Friction in pipes acts in the same way as cut- ting down the head a proportional amount; and by cutting down the head, your water motor loses power in direct proportion to the number of feet head lost. This head, obtained by subtracting friction and other losses from the surveyed head, is called the effective head, and determines the amount of power delivered at the nozzle. The tables on pages 66-67 show the friction WATER WHEEL, HOW TO INSTALL IT 65 loss in pipes up to 12 inches in diameter, ac- cording to the amount of water, and the length of pipe. In this example it is seen that a 240-foot static head is reduced by friction to 230.1 feet effective head. By referring to the table we find the wheel fitting these conditions has a nozzle so small that it cuts down the rate of flow of water in the big pipe to 4.4 feet a second, and permits the flow of only 207 cubic feet of water a minute. The actual horsepower of this tube and nozzle, then, can be figured by applying formula (A), Chapter III, allowing 80 per cent for the efficiency of the wheel. Thus: Actual horsepower = " 1 " . To calculate what the horsepower of this tube 12 inches in diameter and 900 feet long, would be without a nozzle, under a head of 240 feet, introduces a new element of friction losses, which is too complicated to figure here. Such a condition would not be met 66 ELECTRICITY FOR THE FARM 00 ! Q fl* g 2 tfl > OD O S w 5 g 2 I W ^ H O) rt ^ m K M o> "tj +j " : o s sJ o Q ^ g 8 g sill CO ^ I s 1 5 t> TH 05 rH gO ri '-iOrHio^t-0 <-H ,H 01 TH GO CO'OO^CO^OOOOS^t-Ci OJ i-H i-t 0* rH GO S Tf( l> CM THi-iT-IO* >0 t- 5 55 CO^lOOt-CO OjHCS. WATER WHEEL, HOW TO INSTALL IT 67 00 r-HH OO O 05 * O O o -.' 00 10 >O00'-O o in OOOC500^5'^'OtO5O'- | COi-'Cfl' iO- tvj cS g cS^i " a-2-Sl ^ * o I If I pq S o> ** till *~a ojj Ills I 1 ^Jfe^ 68 ELECTRICITY FOR THE FARM with in actual practice, in any event. The largest nozzles used, even in the jumbo plants of the Far West, rarely exceed 10 inches in diameter; and the pipe conveying water to such a nozzle is upwards of eight feet in diame- ter. Steel tubing for supply pipes, from 3 to 12 inches in diameter is listed at from 20 cents to $1.50 a foot, according to the diameter and thickness of the material. Discounts on these prices will vary from 25 to 50 per cent. The farmer can cut down the cost of this pipe by conveying his supply water from its natural source to a pond, by means of an open race, or a wooden flume. An in- genious mechanic can even construct his own pipe out of wood, though figuring labor and materials, it is doubtful if anything would be saved over a riveted steel pipe, purchased at the regular price. This pipe, leading from the pond, or forebay, to the water wheel, should be kept as short as possible; at the same time, the fall should not be too sharp. An angle of 30 will be found very satisfac- WATER WHEEL, HOW TO INSTALL IT 69 tory, although pipe is frequently laid at angles up to 50. Other Types of Impulse Wheels In recent years more efficient forms of the old-fashioned overshoot, pitch-back breast, and undershoot wheels have been developed, by substituting steel or other metal for wood, and altering the shape of the buckets to make better use of the power of falling water. In some forms of overshoot wheels, an efficiency of over 90 per cent is claimed by manufacturers; and this type offers the addi- tional advantage of utilizing small quantities of water, as well as being efficient under varying quantities of water. They utilize the falling weight of water, although by giving the water momentum at the point of delivery, by means of the proper fall, impulse too is utilized in some measure. The modern steel overshoot wheel receives water in its buckets from a spout set a few degrees back of dead center; and its buckets are so shaped that the water is retained a full half- 70 ELECTRICITY FOR THE FARM revolution of the wheel. The old-style over- shoot wheel was inefficient principally be- cause the buckets began emptying themselves at the end of a quarter-revolution. An- other advantage claimed for these wheels over the old style is that, being made of thin metal, their buckets attain the tempera- ture of the water itself, thus reducing the danger of freezing to a minimum. They are manufactured in sizes from 6 feet in diameter to upwards of fifty feet; and with buckets of from 6 inches to 10 feet in width. In prac- tice it is usual to deliver water to the buckets by means of a trough or pipe, through a suit- able spout and gate, at a point two feet above the crown of the wheel. For this reason, the diameter of the wheel corresponds very closely to the head in feet. The Reaction Turbine The reaction turbine is best adapted to low heads, with a large supply of water. It is not advisable, under ordinary circumstances, to use it under heads exceeding 100 feet, as WATER WHEEL, HOW TO INSTALL IT 71 its speed is then excessive. It may be used under falls as low as two feet. Five thousand cubic feet of water a minute would give ap- proximately 14 actual horsepower under such a head. A sluggish creek that flows in large volume could thus be utilized for power with the reaction turbine, whereas it would be useless with an impulse wheel. Falls of from five to fifteen feet are to be found on thousands of farm streams, and the reaction turbine is admirably adapted to them. Reaction turbines consist of an iron "run- ner" which is in effect a rotary fan, the pres- sure and momentum of the column of water pressing on the slanted blades giving it motion and power. These wheels are manufactured in a great variety of forms and sizes; and are to be purchased either as the runner (set in bearings) alone, or as a runner enclosed in an iron case. In case the runner alone is pur- chased, the owner must enclose it, either with iron or wood. They vary in price according to size, and the means by which the flow of water is controlled. A simple 12-inch reaction 72 ELECTRICITY FOR THE FARM turbine wheel, such as would be suitable for many power plants can be had for $75. A twelve-inch wheel, using 18 or 20 square inches of water, would generate about 7J^ horsepower under a 20-foot head, with 268 cubic feet of water a minute. Under a 30- foot head, and with 330 cubic feet of water such a wheel will give 14 horsepower. A 36-inch wheel, under a 5-foot head, would use 2,000 cubic feet of water, and give 14 horsepower. Under a 30-foot head, this same wheel, using 4,900 cubic feet of water a minute, would develop over 200 horse- power. If the farmer is confronted by the situation of a great deal of water and small head, a large wheel would be necessary. Thus he could secure 35 horsepower with only a 3 -foot head, providing his water supply is equal to the draft of 8,300 cubic feet a minute. From these sample figures, it will be seen that the reaction turbine will meet the re- quirements of widely varying conditions up to, say a head of 100 feet. The farmer pros- pector should measure first the quantity of WATER WHEEL, HOW TO INSTALL IT 73 A typical vertical turbine 74 ELECTRICITY FOR THE FARM water to be depended on, and then the num- ber of feet fall to be had. The higher the fall, with certain limits, the smaller the ex- pense of installation, and the less water re- quired. When he has determined quantity and head, the catalogue of a reputable manu- facturer will supply him with what informa- tion is necessary to decide on the style and size wheel he should install. In the older settled communities, especially in New Eng- land, a farmer should be able to pick up a second-hand turbine, at half the price asked for a new one; and since these wheels do not depreciate rapidly, it would serve his purpose as well, in most cases, as a new one. Reaction turbines may be either horizon- tal or vertical. If they are vertical, it is necessary to connect them to the main shaft by means of a set of bevel gears. These gears should be substantially large, and if the teeth are of hard wood (set in such a manner that they can be replaced when worn) they will be found more satisfactory than if of cast or cut metal. WATER WHEEL, HOW TO INSTALL IT 75 The horizontal turbine is keyed to its shaft, like the impulse wheel, so that the wheel shaft itself is used for driving, without gears or a quarter-turn belt. (The latter is to be avoided, wherever possible.) There are many forms of horizontal turbines; they are to be had of the duplex type, that is, two wheels on one shaft. These are arranged so that Two wheels on a horizontal shaft (Courtesy of the C. P. Bradway Company, West Stafford, Conn.) either wheel may be run separately, or both together, thus permitting one to take advan- tage of the seasonal fluctuation in water supply. A convenient form of these wheels includes draft tubes, by which the wheel may be set several feet above the tailrace, and the advantage of this additional fall still be preserved. In this case the draft tube must be airtight so as to form suction, when 76 ELECTRICITY FOR THE FARM filled with escaping water, and should be pro- portioned to the size of the wheel. Theo- retically these draft tubes might be 34 feet long, but in practice it has been found that they should not exceed 10 or 12 feet under ordinary circumstances. They permit the wheel to be installed on the main floor of the power station, with the escape below, instead of being set just above the tailrace level itself, as is the case when draft tubes are not used. Reaction turbines when working under a variable load require water governors (like impulse wheels) although where the supply of water is large, and the proportion of power between water wheel and dynamo is liberal say two to one, or more this necessity is greatly reduced. Reaction wheels as a rule govern themselves better than impulse wheels, due both to the fact that they use more water, and that they operate in a small airtight case. The centrifugal ball governor is the type usually used with reaction wheels as well as with impulse wheels. This subject will be discussed more fully later. WATER WHEEL, HOW TO INSTALL IT 77 Installing a Power Plant In developing a power prospect, the dam itself is usually not the site of the power plant. In fact, because of danger from flood water and ice, it is better to locate it in a more pro- tected spot, leading the water to the wheel by means of a race and flume. A typical crib dam, filled with stone, is shown in section in the diagram, and the half-tone illustration shows such a dam hi course of construction. The first bed of tim- bers should be laid on hard-pan or solid rock in the bed of the stream parallel to its flow. The second course, across the stream, is then begun, being spiked home by means of rods cut to length and sharpened by the local blacksmith, from %-inch Norway iron. Hem- lock logs are suitable for building the crib; and as the timbers are finally laid, it should be filled in and made solid with boulders. This filling in should proceed section by section, as the planking goes forward, other- wise there will be no escape for the water of the 78 ELECTRICITY FOR THE FARM WATER WHEEL, HOW TO INSTALL IT 79 stream, until it rises and spills over the top timbers. The planking should be of two-inch chestnut, spiked home with 60 penny wire spikes. When the last section of the crib is filled with boulders and the water rises, the remaining planks may be spiked home with the aid of an iron pipe in which to drive the KIVER BED SILT A A A- HEMLOCK LOGS PARALLEL, TO FLOW Of STREAM BBS- HEM LOCK LOGS ACROSS FLOW Of -STAEAft CC-- .' CHESTNUT PLAlVKLPfO EBE ~ BOWLDERS JJESTE& 2N LO& CKJ3 Cross-section of a rock and timber dam spike by means of a plunger of iron long enough to reach above the level of the water. When the planking is completed, the dam should be well gravelled, to within a foot or two of its crest. Such dams are substantial, easily made with the aid of unskilled labor, and the materials are to be had on the average farm with the exception of the hardware. This dam forms a pond from which the race 80 ELECTRICITY FOR THE FARM draws its supply of water for the wheel. It also serves as a spillway over which the surplus water escapes. The race should enter the pond at some convenient point, and should be protected at or near its point of entrance by a bulkhead containing a gate, so that the supply of water may be cut off from the race and wheel readily. The lay of the land will determine the length and course of the race. The object of the race is to secure the re- quired head by carrying a portion of the available water to a point where it can escape, by a fall of say 30 to the tailrace. It may be feasible to carry the race in a line almost at right angles to the stream itself, or, again, it may be necessary to parallel the stream. If the lay of the land is favorable, the race may be dug to a distance of a rod or so inshore, and then be permitted to cut its own course along the bank, preventing the water escaping back to the river or brook before the site of the power plant is reached, by building suitable retaining embankments. The race should be of ample size for conveying the water required WATER WHEEL, HOW TO INSTALL IT 81 without too much friction. It should end in a flume constructed stoutly of timbers. It is from this flume that the penstock draws water for the wheel. When the wheel gate is closed the water in the mill pond behind the dam, and in the flume itself should maintain an approximate level. Any surplus flow is per- mitted to escape over flushboards in the flume; these same flushboards main- tain a constant head when the wheel is in opera- tion by carrying off what little sur- plus water the race delivers from the pond. At some point in tne race Or # A -MUDSILLS -SUNK FLUSH wrm 'BED OF 'RACE SB END PLANKING flnrn*> \\\C flrVO/ C C ~ PLAMONG UALHW DOWN IftSltE OF GATE SLOT I1UII1C, LilC IIUW O -GATE W~ WATER CHANNEL Should be pro- Detail of bulkhead gate tected from leaves and other trash by means of a rack. This rack is best made of \4 or 82 ELECTRICITY FOR THE FARM i/2-inch battens from 1J^ to 3 inches in width, bolted together on their flat faces and separated a distance equal to the thick- ness of the battens by means of iron washers. This rack will accumulate leaves and trash, varying with the time of year and should be kept clean, so as not to cut down the supply of water needed by the wheel. The penstock, or pipe conveying water from the flume to the wheel, should be constructed of liberal size, and substantially, of two-inch chestnut planking, with joints caulked with oakum, and the whole well bound together to resist the pressure of the water. Means should be provided near the bottom for an opening through which to remove any obstructions that may by accident pass by the rack. Many wheels have plates provided in their cases for this purpose. The tailrace should be provided with enough fall to carry the escaping water back to the main stream, without backing up on the wheel itself and thus cutting down the head. It is impossible to make any estimates of the WATER WHEEL, HOW TO INSTALL IT 83 cost of such a water-power plant. The labor required will in most instances be supplied by the farmer himself, his sons, and his help, during times when farm operations are slack. Water Rights of the Farmer The farmer owns the bed of every stream not navigable, lying within the boundary lines of the farm; and his right to divert and make use of the water of such streams is determined in most states by common law. In the dry-land states where water is scarce and is valuable for irrigation, a special set of statutes has sprung up with the development of irrigation in this country. A stream on the farm is either public or private; its being navigable or "floatable" (suitable for floating logs) determining which. Water rights are termed in law "riparian" rights, and land is riparian only when water flows over it or along its borders. Green (Law for the American Farmer) says : " Water is the common and equal property of every one through whose land it flows, 84 ELECTRICITY FOR THE FARM and the right of each land-owner to use and consume it without destroying, or unreason- ably impairing the rights of others, is the same. An owner of land bordering on a run- ning stream has the right to have its waters flow naturally, and none can lawfully divert them without his consent. Each riparian proprietor has an equal right with all the others to have the stream flow in its natural way without substantial reduction in volume, or deterioration in quality, subject to a proper and reasonable use of its waters for domestic, agricultural and manufacturing purposes, and he is entitled to use it himself for such pur- poses, but in doing so must not substantially injure others. In addition to the right of drawing water for the purposes just men- tioned, a riparian proprietor, if he duly re- gards the rights of others, and does not un- reasonably deplete the supply, has also the right to take the water for some other proper uses." Thus, the farmer who seeks to develop water- power from a stream flowing across his own WATER WHEEL, HOW TO INSTALL IT 85 land, has the right to divert such a stream from its natural channel providing it is not a navigable or floatable stream but in so doing, he must return it to its own channel for lower riparian owners. The generation of water-power does not pollute the water, nor does it diminish the water in quantity, therefore the farmer is infringing on no other owner's rights in using the water for such a purpose. When a stream is a dividing line between two farms, as is frequently the case, each proprietor owns to the middle of the stream and controls its banks. Therefore to erect a dam across such a private stream and divert all or a part of the water for power purposes, requires the consent of the neighboring owner. The owner of the dam is responsible for dam- age due to flooding, to upstream riparian owners. PART H ELECTRICITY CHAPTER V THE DYNAMO; WHAT IT DOES, AND HOW Electricity compared to the heat and light of the Sun The simple dynamo The amount of electric energy a dynamo will generate The modern dynamo Measuring power in terms of electric- ityThe volt The ampere The ohm The watt and the kilowatt Ohm's Law of the electric circuit, and some examples of its application Direct current, and alternating current Three types of direct-current dynamos: series, shunt, and compound. WHAT a farmer really does in generating electricity from water that would otherwise run to waste in his brook, is to install a private Sun of his own which is on duty not merely in daylight, but twenty-four hours a day; a private Sun which is under such simple con- trol that it shines or provides heat and power, when and where wanted, simply by touching a button. This is not a mere fanciful statement. When you come to look into it you find that 90 ELECTRICITY FOR THE FARM electricity actually is the life-giving power of the Sun's rays, so transformed that it can be handily conveyed from place to place by means of wires, and controlled by mechanical devices as simple as the spigot that drains a cask. Nature has the habit of traveling in circles. Sometimes these circles are so big that the part of them we see looks like a straight line, but it is not. Even parallel lines, according to the mathematicians, "meet in infinity." Take the instance of the water wheel which the farmer has installed under the fall of his brook. The power which turns the wheel has the strength of many horses. It is there in a handy place for use, because the Sun brought it there. The Sun, by its heat, lifted the water from sea-level, to the pond where we find it and we cannot get any more power out of this water by means of a turbine using its pressure and momentum in falling, than the Sun itself expended in raising the water against the force of gravity. Once we have installed the wheel to change the energy of falling water into mechanical DYNAMO; WHAT IT DOES, AND HOW 91 power, the task of the dynamo is to turn this mechanical power into another mode of mo- tion electricity. And the task of electricity is to change this mode of motion back into the original heat and light of the Sun which started the circle in the beginning. Astronomers refer to the Sun as "he" and "him" and they spell his name with a capital letter, to show that he occupies the center of our small neighborhood of the universe at all times. Magnets and Magnetism The dynamo is a mechanical engine, like the steam engine, the water turbine or the gas engine; and it converts the mechanical motion of the driven wheel into electrical motion, with the aid of a magnet. Many scientists say that the full circle of energy that keeps the world spinning, grows crops, and paints the sky with the Aurora Borealis, begins and ends with magnetism that the sun's rays are magnetic rays. Magnetism is the force that keeps the compass needle pointing north 92 ELECTRICITY FOR THE FARM and south. Take a steel rod and hold it along the north and south line, slightly inclined towards the earth, and strike it a sharp blow with a hammer, and it becomes a magnet feeble, it is true, but still a magnet. Take a wire connected with a common dry battery and hold a compass needle under it and the needle will immediately turn around and point directly across the wire, showing that the wire possesses magnetism encircling it in invisible lines, stronger than the mag- netism of the earth. Insulate this wire by covering it with cotton thread, and wind it closely on a spool. Con- nect the two loose ends to a dry battery, and you will find that you have multiplied the magnetic strength of a single loop of wire by the number of turns on the spool concen- trated all the magnetism of the length of that wire into a small space. Put an iron core in the middle of this spool and the magnet seems still more powerful. Lines of force which otherwise would escape in great circles into space, are now concentrated in the iron. The DYNAMO; WHAT IT DOES, AND HOW 93 iron core is a magnet. Shut off the current from the battery and the iron is still a mag- net weak, true, but it will always retain a small portion of its magnetism. Soft iron retains very little of its magnetism. Hard steel retains a great deal, and for this reason steel is used for permanent magnets, of the horseshoe type so familiar. A Simple Dynamo A dynamo consists, first, of a number of such magnets, wound with insulated wire. Their iron cores point towards the center of a circle like the spokes of a wheel; and their curved inner faces form a circle in which a spool, w^ound with wire in another way, may be spun by the water wheel. Now take a piece of copper wire and make a loop of it. Pass one side of this loop in front of an electric magnet. As the wire you hold in your hands passes the iron face of the magnet, a wave of energy that is called electricity flows around this loop at the rate of 186,000 miles a second the 94 ELECTRICITY FOR THE FARM same speed as light comes to us from the sun. As you move the wire away from the magnet, a second wave starts through the wire, flowing in the opposite direction. You can prove this by holding a compass needle under the wire and see it wag first in one direction, then in another. A wire "cutting" the lines of force of an electro-magnet This is a simple dynamo. A wire "cutting" the invisible lines of force, that a magnet is spraying out into the air, becomes "electri- fied." Why this is true, no one has ever been able to explain. The amount of electricity its capacity for work which you have generated with the magnet and wire, does not depend alone on the pulling power of that simple magnet. Let us say the magnet is very weak has not enough power to lift one ounce of iron. Never- DYNAMO; WHAT IT DOES, AND HOW 95 theless, if you possessed the strength of Hercules, and could pass that wire through the field of force of the magnet many thou- sands of times a second, you would generate enough electricity in the wire to cause the wire to melt in your hands from heat. \ Cross-section of an armature revolving in its field This experiment gives the theory of the dynamo. Instead of passing only one wire through the field of force of a magnet, we have hundreds bound lengthwise on a revolving drum called an armature. Instead of one magnetic pole in a dynamo we have two, or 96 ELECTRICITY FOR THE FARM four, or twenty according to the work the machine is designed for always in pairs, a North pole next to a South pole, so that the lines of force may flow out of one and into another, instead of escaping in the surrounding air. If you could see these lines of force, they would appear in countless numbers issuing from each pole face of the field magnets, Forms of annealed steel discs used in armature construction pressing against the revolving drum like hair brush bristles trying to hold it back. This drum, in practice, is built up of discs of annealed steel, and the wires extending length- wise on its face are held in place by slots to prevent them from flying off when the drum is whirled at high speed. The drum does not touch the face of the magnets, but revolves in an air space. If we give the electric impulses generated in these wires a chance to flow in a DYNAMO; WHAT IT DOES, AND HOW 97 circuit flow out of one end of the wires, and in at the other, the drum will require more and more power to turn it, in proportion to the amount of electricity we permit to flow. Thus, if one electric light is turned on, the drum will press back with a certain strength on the water wheel; if one hundred lights are turned An armature partly wound, showing slots and commutator on it will press back one hundred times as much. Providing there is enough power hi the water wheel to continue turning the drum at its predetermined speed, the dynamo will keep on giving more and more electricity if asked to, until it finally destroys itself by fire. You cannot take more power, in terms of elec- tricity, out of a dynamo that you put into it, in terms of mechanical motion. In fact, 98 ELECTRICITY FOR THE FARM to insure flexibility and constant speed at all loads, it is customary to provide twice as much water wheel, or engine, power as the electrical rating of the dynamo. We have seen that a water wheel is 85 per cent efficient under ideal conditions. A dynamo's efficiency in translating mechanical motion into electricity, varies with the type of machine and its size. The largest machines attain as high as 90 per cent efficiency; the smallest ones run as low as 40 per cent. Measuring Electric Power The amount of electricity any given dynamo can generate depends, generally speaking, on two factors, i. e., (1) the power of the water wheel, or other mechanical engine that turns the armature; and (2) the size (carrying capacity) of the wires on this drum. Strength, of electricity, is measured in am- peres. An ampere of electricity is the unit of the rate of flow and may be likened to a gallon of water per minute. in surveying for water-power, in Chapter DYNAMO; WHAT IT DOES, AND HOW 99 III, we found that the number of gallons or cubic feet of water alone did not determine the amount of power. We found that the number of gallons or cubic feet multiplied by the distance in feet it falls in a given time, was the determining factor pounds (quantity) multi- plied by feet per second (velocity). Showing the analogy of water to volts and amperes of electricity The same is true in figuring the power of electricity. We multiply the amperes by the number of electric impulses that are created in the wire in the course of one second. The unit of velocity, or pressure of the electric current is called a volt. Voltage is the pressure which causes electricity to flow. A volt may be likened to the velocity in feet per second of water in falling past a certain point. If you 100 ELECTRICITY FOR THE FARM think a moment you will see that this has nothing to do with quantity. A pin-hole stream of water under 40 pounds pressure has the same velocity as water coming from a nozzle as big as a barrel, under the same pres- sure. So with electricity under the pressure of one volt or one hundred volts. One volt is said to consist of a succession of impulses caused by one wire cutting 100,000,000 lines of magnetic force in one second. Thus, if the strength of a magnet consisted of one line of force, to create the pressure of one volt we would have to "cut" that line of force 100,000,000 times a second, with one wire; or 100,000 times a second with one thousand wires. Or, if a magnet could be made with 100,000,000 lines of force, a single wire cutting those lines once in a second would create one volt pressure. In actual practice, field mag- nets of dynamos are worked at densities up to and over 100,000 lines of force to the square inch, and armatures contain several hundred conductors to "cut" these magnetic lines. The voltage then depends on the speed at DYNAMO; WHAT IT DOES,- N1> IStiti \ which the armature is driven. In machines for isolated plants, it will be found that the speed varies from 400 revolutions per minute, to 1,800, according to the design of dynamo used. Multiplying amperes (strength) by volts (pressure), gives us watts (power). Seven hundred and forty-six watts of electrical energy is equal to one horsepower of me- chanical energy will do the same work. Thus an electric cur- rent under a pres- sure of 100 volts, l-\~4 +-"-4 I*?p4 j.;j} and a density of Pressure determines volume of flow 7.46 amperes, is one in a * yea time horsepower; as is 74.6 amperes, at 10 volts pressure; or 746 amperes at one volt pressure. For convenience (as a watt is a small quantity) electricity is measured in kilowatts, or 1,000 watts. Since 746 watts is one horsepower, 1,000 watts or one kilowatt is 1.34 horsepower. The work of such a current for one hour is called a kilowatt-hour, and in our cities, where electricity is generated from steam, the retail ELECTRICITY FOR THE FARM price of a kilowatt-hour varies from 10 to 15 cents. Now as to how electricity may be controlled, so that a dynamo will not burn itself up when it begins to generate. Again we come back to the analogy of water. The amount of w r ater that passes through a pipe in any given time, depends on the size of the pipe, if the pressure is maintained uniform. In other words the resistance of the pipe to the flow of water determines the amount. If the pipe be the size of a pin- hole, a very small amount of water will escape. If the pipe is as big around as a barrel, a large amount will force its way through. So with electricity. Resistance, introduced in the electric circuit, controls the amount of current that flows. A wire as fine as a hair will permit only a small quantity to pass, under a given pressure. A wire as big as one's thumb will permit a correspondingly greater quantity to pass, the pressure remaining the same. The unit of electrical resistance is called the ohm named after a man, as are all electrical units. DYNAMO; WHAT IT DOES, AND HOW 103 Ohms Law The ohm is that amount of resistance that will permit the passage of one ampere, under the pressure of one volt. It would take two volts to force two amperes through one ohm; or 100 volts to force 100 amperes through the resistance of one ohm. From this we have Ohm's Law, a simple formula which is the beginning and end of all electric computations the farmer will have to make in installing his water-power electric plant. Ohm's Law tells us that the density of current (amperes) that can pass through a given resistance in ohms (a wire, a lamp, or an electric stove) equals volts divided by ohms or pressure divided by resistance. This formula may be written in three ways, thus : C = |, or R = or, E = C x R. Or to ex- press the same thing in words, current equals volts divided by ohms; ohms equals volts divided by current; or volts equals current multiplied by ohms. So, with any two of these three deter- mining factors known, we can find the third. 104 ELECTRICITY FOR THE FARM As we have said, this simple law is the begin- ning and end of ordinary calculations as to electric current, and it should be thoroughly understood by any farmer who essays to be his own electrical engineer. Once understood and applied, the problem of the control of the electric current becomes simple a b c. Examples of Ohm's Law Let us illustrate its application by an example. The water wheel is started and is spinning the dynamo at its rated speed, say 1,500 r. p. m. Two heavy wires, leading from brushes which collect electricity from the revolving armature, are led, by suitable in- sulated supports to the switchboard, and fastened there. They do not touch each other. Dynamo mains must not be permitted to touch each other under any conditions. They are separated by say four inches of air. Dry air is a very poor conductor of electricity. Let us say, for the example, that dry air has a resistance to the flow of an electric current, of 1,000,000 ohms to the inch that would be DYNAMO; WHAT IT DOES, AND HOW 105 4,000,000 ohms. How much electricity is being permitted to escape from the armature of this 110-volt dynamo, when the mains are separated by four inches of dry air? Apply Ohm's law, C equals E divided by R. E, in this case is 110; R is 4,000,000; therefore C (amperes) equals 110/4,000,000 an infinites- imal amount about .0000277 ampere. Let us say that instead of separating these two mains by air we separated them by the human body that a man took hold of the bare wires, one in each hand. The resistance of the human body varies from 5,000 to 10,000 ohms. In that case C (amperes) equals 110/5,000, or 110/10,000 about l/50th, or 1/1 00th of an ampere. This illustrates why an electric current of 110 volts pres- sure is not fatal to human beings, under ordinary circumstances. The body offers too much resistance. But, if the volts were 1,100 instead of the usual 110 used in com- mercial and private plants for domestic use, the value of C, by this formula at 5,000 ohms, would be nearly 1/5 th ampere. To drive l/5th 106 ELECTRICITY FOR THE FARM ampere of electricity through the human body would be fatal in many instances. The higher the voltage, the more dangerous the current. In large water-power installations in the Far West, where the current must be transmitted over long distances to the spot where it is to be used, it is occasionally generated at a pres- sure of 150,000 volts. Needless to say, contact with such wires means instant death. Before being used for commercial or domestic pur- poses, in such cases, the voltage is "stepped down" to safe pressures to 110, or to 220, or to 550 volts always depending on the use made of it. Now, if instead of interposing four inches of air, or the human body, between the mains of our 110- volt dynamo, we connected an incandescent lamp across the mains, how much electricity would flow from the gen- erator? An incandescent lamp consists of a vacuum bulb of glass, in which is mounted a slender thread of carbonized fibre, or fine tungsten wire. To complete a circuit, the current must flow through this wire or fila- DYNAMO; WHAT IT DOES, AND HOW 107 ment. In flowing through it, the electric current turns the wire or filament white hot incandescent and thus turns electricity back into light, with a small loss in heat. In an ordinary 16 candlepower carbon lamp, the resistance of this filament is 220 ohms. There- fore the amount of current that a 110-volt generator can force through that filament is or }/ ampere. Armature and field coils of a direct current dynamo One hundred lamps would provide 100 paths of 220 ohms resistance each to carry current, and the amount required to light 100 such lamps would be 100 x ^ or 50 amperes. Every electrical device a lamp, 108 ELECTRICITY FOR THE FARM a stove, an iron, a motor, etc., must, by regulations of the Fire Underwriters' Board be plainly marked with the voltage of the current for which it is designed and the amount of current it will consume. This is usually done by indicating its capacity in watts, which as we have seen, means volts times amperes, and from this one can figure ohms, by the above formulas. A Short Circuit We said a few paragraphs back that under no conditions must two bare wires leading from electric mains be permitted to touch each other, without some form of resistance being interposed in the form of lamps, or other devices. Let us see what would happen if two such bare wires did touch each other. Our dynamo as we discover by reading its plate, is rated to deliver 50 amperes, let us say, at 110 volts pressure. Modern dynamos are rated liberally, and can stand 100% overload for short periods of time, without dangerous overheating. Let us say that the DYNAMO; WHAT IT DOES, AND HOW 109 mains conveying current from the armature to the switchboard are five feet long, and of No. 2 B. & S. gauge copper wire, a size which will carry 50 amperes without heating appre- ciably. The resistance of this 10 feet of No. 2 copper wire, is, as we find by consulting a wire table, .001560 ohms. If we touch the ends of these two five-foot wires together, we instantly open a clear path for the flow of electric current, limited only by the carrying capacity of the wire and the back pressure of .001560 ohms resistance. Using Ohm's Law, C equals E divided by R, we find that C (amperes) equals .WiVW or 70,515 amperes! Unless this dynamo were properly pro- tected, the effect of such a catastrophe would be immediate and probably irrepara- ble. In effect, it Would A direct current dynamo be suddenly exerting a force of nearly 10,000 horsepower against the little 10 horse- power water wheel that is driving this 110 ELECTRICITY FOR THE FARM dynamo. The mildest thing that could hap- pen would be to melt the feed-wire or to snap the driving belt, in which latter case the dynamo would come to a stop. If by any chance the little water wheel was given a chance to maintain itself against the blow for an instant, the dynamo, rated at 50 am- peres, would do its best to deliver the 70,515 amperes you called for and the result would be a puff of smoke, and a ruined dynamo. This is called a "short circuit" one of the first "don'ts" in handling electricity. As a matter of fact every dynamo is pro- tected against such a calamity by means of safety devices, which will be described in a later chapter because no matter how care- ful a person may be, a partial short circuit is apt to occur. Happily, guarding against its disastrous effects is one of the simplest prob- lems in connection with the electric plant. Direct Current and Alternating Current When one has mastered the simple Ohm's Law of the electric circuit, the next step is to DYNAMO; WHAT IT DOES, AND HOW 111 determine what type of electrical generator is best suited to the requirements of a farm plant. In the first place, electric current is divided into two classes of interest here alternating, and direct. We have seen that when a wire is moved through the field of a magnet, there is induced in it two pulsations first in one direction, then in another. This is an alternating cur- rent, so called because it changes its direction. If, with our armature containing hundreds of wires to "cut" the lines of force of a group of magnets, we connected the beginning of each wire with one copper ring, and the end of each wire with another copper ring, we would have what is called an alternating- current dynamo. Simply by pressing a strap of flexible copper against each revolving copper ring, we would gather the sum of the current of these conductors. Its course would be represented by the curved line in the diagram, one loop on each side of the middle line (which represents time) would be a cycle. The num- 112 ELECTRICITY FOR THE FARM her of cycles to the second depends on the speed of the armature; in ordinary practice it is usually twenty-five or sixty. Alternat- ing current has many advantages, which however, do not concern us here. Except under very rare conditions, a farmer installing his own plant should not use this type of machine. WAVE REFGEaENTING BACK-AND-FCKTH FLOW OF ALTERNATING CV&RNT LOfE RPI3StfTlIfG FLOW OF DIRECT Diagram of alternating and direct current If, however, instead of gathering all the current with brushes bearing on two copper rings, we collected all the current traveling in one direction, on one set of brushes and all the current traveling in the other di- rection on another set of brushes, we would straighten out this current, make it all travel in one dire^ion. Then we would have a direct current. A direct current dynamo, the type generally used in private plants, does DYNAMO; WHAT IT DOES, AND HOW 113 this. Instead of having two copper rings for collecting the current, it has a single ring, made up of segments of copper bound together, but insulated from each other, one segment for each set of conductors on the armature. This ring of many segments, is called a commuta- tor, because it commutates, or changes, the direction of the electric impulses, and delivers them all in one direction. In effect, it is like the connecting rod of a steam engine that straightens out the back-and-forth motion of the piston in the steam cylinder and delivers the motion to a wheel running in one direction. Such a current, flowing through a coil of wire would make a magnet, one end of which would always be the north end, and the other end the south end. An alternating cur- rent, on the other hand, flowing through a coil of wire, would make a magnet that changed its poles with each half-cycle. It would no sooner begin to pull another mag- net to it, than it would change about and push the other magnet away from it, and so on, as long as it continued to flow. This 114 ELECTRICITY FOR THE FARM is one reason why a direct current dynamo is used for small plants. Alternating current will light the same lamps and heat the same irons as a direct current; but for electric power it requires a different type of motor. Types of Direct Current Dynamos Just as electrical generators are divided into two classes, alternating and direct, so j direct current machines are divided into three classes, according to the manner in which their output, in amperes and volts, is regulated. They differ as to the manner in which their field magnets (in whose field of force the armature spins) are excited, or made mag- netic. They are called series, shunt, and compound machines. The Series Dynamo By referring to the diagram, it will be seen j that the current of a series dynamo issues from the armature mains, and passes through the coils of the field magnets before passing into the external circuit to do its work. The DYNAMO; WHAT IT DOES, AND HOW 115 residual magnetism, or the magnetism left in the iron cores of the field magnets from its last charge, provides the initial excitation, when the machine is started. As the resis- tance of the external circuit is lowered, by turning on more and more lights, more and more current flows from the armature, through the field magnets. Each time the resistance is lowered, therefore, the current passing through the field magnets becomes more dense in amperes, and makes the field magnets correspondingly stronger. We have seen that the voltage depends on the number of lines of magnetic force cut by the armature conductors in a given time. If the speed remains constant then, and the magnets grow stronger and stronger, the volt- age will rise in a straight line. When no cur- rent is drawn, it is 0; at full load, it may be 100 volts, or 500, or 1,000 according to the machine. This type of machine is used only in street lighting, in cities, with the lights connected in "series," or one after another on the same wire, the last lamp finally returning 116 ELECTRICITY FOR THE FARM the wire to the machine to complete the cir- cuit. This type of dynamo has gained the name f r itself of "mankiller," as its voltage becomes enor- mous at full load. It is unsuitable, in every respect, for the farm plant. Its field coils Connections of a series dynamo consist of a f CW turns of very heavy wire, enough to carry all the cur- rent of the external circuit, without heating. The Shunt Dynamo The shunt dynamo, on the other hand, has field coils connected directly across the cir- cuit, from one wire to another, instead of in "series." These coils consist of a great many turns of very fine wire, thus introducing resistance into the circuit, which limits the amount of current (amperes) that can be forced through them at any given voltage. As a shunt dynamo is brought up to its rated speed, its voltage gradually rises until a con- DYNAMO; WHAT IT DOES, AND HOW 117 dition of balance occurs between the field coils and the armature. There it remains con- stant. When re- I ToLoad sistance on the ex- * ternal circuit is lowered, by means of turning on lamps or other de- vices, the current from the armature increases in work- Connections of a shunt dynamo ing power, by increasing its amperes. Its voltage remains stationary; and, since the resistance of its field coils never changes, the magnets do not vary in strength. The objection to this type of machine for a farm plant is that, in practice, the armature begins to exercise a de-magnetizing effect on the field magnets after a certain point is reached weakens them; consequently the voltage begins to fall. The voltage of a shunt dynamo begins to fall after half -load is reached; and at full load, it has fallen pos- sibly 20 per cent. A rheostat, or resistance 118 ELECTRICITY FOR THE FARM box on the switchboard, makes it possible to cut out or switch in additional resistance in the field coils, thus varying the strength of the field coils, within a limit of say 15 per cent, to keep the voltage constant. This, however, requires a constant attendance on the machine. If the voltage were set right for 10 lights, the lights would grow dim when 50 lights were turned on; and if it were ad- justed for 50 lights, the voltage would be too high for only ten lights would cause them to "burn out." Shunt dynamos are used for charging storage batteries, and are satisfactory for direct service only when an attendant is constantly at hand to regulate them. The Compound Dynamo The ideal between these two conditions would be a compromise, which included the characteristics of both series and shunt effects. That is exactly what the compound dynamo effects. A compound dynamo is a shunt dynamo DYNAMO; WHAT IT DOES, AND HOW 119 with just enough series turns on its field coils, to counteract the de-magnetizing effect of the armature at full load. A machine can be designed to make the voltage rise gradually, or swiftly, by combining the two systems. For country homes, the best combination is a machine that will keep the voltage constant from no load to full load. A so-called flat- compounded machine does this. In actual practice, this voltage rises slightly at the half- load line only two or three volts, which will not damage the lamps in a 110- volt circuit. The compound dynamo is therefore self- regulating, and requires no attention, except as to lubrication, and the incidental care given to any piece of machinery. Any shunt dynamo can be made into a compound dy- namo, by winding a few turns of heavy in- sulated wire around the shunt coils, and con- necting them in "series" with the external circuit. How many turns are necessary de- pends on conditions. Three or four turns to each coil usually are sufficient for "flat com- pounding." If the generating plant is a long 120 ELECTRICITY FOR THE FARM distance from the farm house where the light, heat, and power are to be used, the voltage drops at full load, due to resistance of the trans- mission wires. To overcome this, enough turns can be wound on top of the shunt coils to cause the volt- age to rise at the switchboard, but remain stationary at tne s P ot where the current is used. The usual so-called flat -compounded Connections of a compound dynamo dynamo, turned out by manufacturers, provides for constant voltage at the switchboard. Such a dynamo is eminently fitted for the farm electric plant. Any other type of machine is bound to cause constant trouble and annoyance. CHAPTER VI WHAT SIZE PLANT TO INSTALL The farmer's wife his partner Little and big plants Limiting factors Fluctuations in water supply The average plant The actual plant Amount of current required for various operations Stand- ard voltage A specimen allowance for electric light Heating and cooking by electricity Elec- tric power: the electric motor. THE farmer's wife becomes his partner when he has concluded the preliminary measure- ments and surveys for building his water- power electric plant. Now the question is, how big a plant is necessary, or how small a plant can he get along with. Electricity may be used for a multitude of purposes on the farm, in its sphere of furnishing portable light, heat and power; but when this multitude of uses has been enumerated, it will be found that the wife shares in the benefits no less than the farmer himself. The greatest dividend of all, 121 ELECTRICITY FOR THE FARM whether dividends are counted in dollars or happiness, is that electricity takes the drudg- ery out of housework. Here, the work of the farmer himself ends when he has brought electricity to the house, just as his share in housework ends when he has brought in the kerosene, and filled the woodbox. Of the light and heat, she will use the lion's share; and for the power, she will discover heretofore undreamed-of uses. So she must be a full partner when it comes to deciding how much electricity they need. How much electricity, in terms of light, heat, and power, will the farmer and his wife have use for? How big a plant should be installed to meet the needs of keeping house and running the farm? The answer hangs mainly on how much water-power there is available, through all the seasons of the year, with which to generate electricity. Beyond that, it is merely a ques- tion of the farmer's pocketbook. How much money does he care to spend? Electricity is a cumulative "poison." The more one uses WHAT SIZE PLANT TO INSTALL 123 it, the more he wants to use it. After a plant has been in operation a year, the family have discovered uses for electricity which they did not think of in the beginning. For this reason, it is well to put in a plant larger than the needs of the moment seem to require. An electrical horsepower or two one way or another will not greatly change the first cost, and you will always find use for any excess. Once for all, to settle the question of water- power, the water wheel should be twice the normal capacity of the dynamo it drives, in terms of power. This allows for overload, which is bound to occur occasionally; and it also insures smooth running, easy governing, and the highest efficiency. Since the electric current, once the plant is installed, will cost practically nothing, the farmer can afford to ignore the power going to waste, and consider only how to get the best service. The Two Extremes The amount of water to be had to be turned into electricity, will vary with location, and 124 ELECTRICITY FOR THE FARM with the season. It may be only enough, the greater part of the year, for a "toy" plant a very practical toy, by the way one that will keep half a dozen lights burning in the house and barn at one time; under some conditions water may be so scarce that it must be stored for three or four days to get enough power to charge a storage battery for these six or eight lights. A one-quarter, or a one-half kilowatt electrical generator, with a one horsepower (or smaller) wheel, will light a farmstead very satisfactorily much better than kerosene lamps. On the other hand, the driving power of your wheel may be sufficient to furnish 50 or 100 lights for the house, barn, and out-build- ings, and barn-yard and drives; to provide ample current for irons, toasters, vacuum cleaners, electric fans, etc. ; to do all the cook- ing and baking and keep the kitchen boiler hot; and to heat the house in the coldest weather with a dry clean heat that does not vitiate the air, with no ashes, smoke or dust or woodchopping nothing but an electric switch WHAT SIZE PLANT TO INSTALL 125 to turn on and off; and to provide power for motors ranging from tiny ones to run the sewing machine, to one of 15 horsepower to do the threshing. A plant capable of developing from 30 to 50 kilowatts of electricity, and re- quiring from 50 to 100 horsepower at the water wheel, would do all this, depending on the size of the farmstead. One hundred horse- power is a very small water project, in a com- mercial way; and there are thousands of farms possessing streams of this capacity. Fluctuations in Water Supply It would be only during the winter months that such a plant would be driven to its full capacity; and since water is normally plentiful during these months, the problem of power would be greatly simplified. The heaviest draft on such a plant in summer would be during harvesting; otherwise it would be con- fined to light, small power for routine work, and cooking. Thus, a plant capable of meet- ing all the ordinary requirements of the four dry months of summer, when water is apt to 126 ELECTRICITY FOR THE FARM be scarce, doubles or quadruples its capacity during the winter months, to meet the neces- sities of heat for the house. A dynamo requires only as much power to drive it, at any given time, as is being used in terms of electricity. There is some small loss through friction, of course, but aside from this the power required of the prime mover (the water wheel) is always in proportion to the amount of current flowing. When water is scarce, and the demands for current for heating are low, it is good practice to close a portion of the buckets of the turbine wheel with wooden blocks provided for this purpose. It is necessary to keep the speed of the dynamo uniform under all water conditions; and where there is a great fluctuation between high and low water periods, it is frequently necessary to have a separate set of pulleys for full gate and for half -gate. The head must remain the same, under all conditions. Changing the gate is in effect choking or opening the nozzle supplying the wheel, to cut down or increase its consumption of water. WHAT SIZE PLANT TO INSTALL 127 The Average Plant It will be the exceptional plant, however, among the hundreds of thousands to be had on our farms, which will banish not only the oil lamp and kitchen stove, but all coal or wood burning stoves as well which will heat the house in below-zero weather, and provide power for the heavier operations of the farm. Also, on the other hand, it will be the excep- tional plant whose capacity is limited to furnishing a half-dozen lights and no more. A happy medium between these two con- ditions is the plant large enough to supply between five and ten electrical horsepower, in all seasons. Such a plant will meet the needs of the average farm, outside of winter heating and large power operations, and will provide an excess on which to draw in emergencies, or to pass round to one's neighbors. It is such a plant that we refer to when we say that (not counting labor) its cost, under ordinary condi- tions should not greatly exceed the price of one sound young horse for farm work. 128 ELECTRICITY FOR THE FARM Since the plant we described briefly in the first chapter, meets the requirements of this "average plant" let us inquire a little more fully into its installation, maintenance, and cost. An Actual Plant In this instance, the water-power was al- ready installed, running to waste, in fact. The wheel consists of the so-called thirty-six inch vertical turbine, using 185 square inches of water, under a 14-foot head. Water is sup- plied to this wheel by a wooden penstock 33 inches square, inside measurements, and sloping at an angle of 30 from the flume to the wheel. This wheel, under a 14-foot head, takes 2,312 cubic feet of water a minute; and it develops 46.98 actual horsepower (as may be figured by using the formulas of Chapter III). The water supply is provided by a small mountain river. The dam is 10 feet high, and the race, which feeds the flume from the mill pond is 75 yards long. The race has two Details of voltmeter or ammeter WHAT SIZE PLANT TO INSTALL 129 spillways, one near the dam, and the second at the flume itself, to maintain an even head of water at all times. Half-Gate Since the water supply varies with the seasons, it has been found practical to run the wheel at half -gate that is, with the gate only half -open. A set of bevel gears work the main shaft, which runs at approximately 200 revolu- tions per minute; and the dynamo is worked up to its required speed of 1,500 revolutions per minute through a countershaft. The dynamo is a modern four-pole machine, compound-wound, with a rated output of 46 amperes, at 125 volts in other words a dynamo of 5.75 kilowatts capacity, or 7.7 electrical horsepower. At full load this dy- namo would require a driving power of 10 horsepower, counting it as 75 per cent efficient; and, to conform to our rule of two water horsepower to one electrical horsepower, the wheel should be capable of developing 20 horsepower. As a matter of fact, in this 130 ELECTRICITY FOR THE FARM particular instance, shutting down the wheel to half -gate more than halves the rated power of the wheel, and little more than 15 horse- power is available. This allowance has proved ample, under all conditions met with, in this plant. The dynamo is mounted on a firm floor foundation; and it is belted from the counter- shaft by an endless belt running diagonally. A horizontal belt drive is the best. Vertical drive should be avoided wherever possible. The Switchboard The switchboard originally consisted of a wooden frame on which were screwed ordinary asbestos shingles, and the instruments were mounted on these. Later, a sheet of electric insulating fibre was substituted, for look's sake. The main requisite is something substantial and fireproof. The switchboard instruments consist of a voltmeter, with a range of from to 150 volts; an ammeter, with a range, to 75 amperes; a field regulating rheostat (which came with the dynamo); a main switch, with WHAT SIZE PLANT TO INSTALL 131 cartridge fuses protecting the machine against a draft of current over 60 amperes; and two line switches for the two owners, one fuse at 20 am- peres, and the other at 40 amperes. Electric fuses are either cartridges or plugs, en- closing lead wire of a size corresponding to their rating. All the current of the line they protect passes through this lead wire. If the current drawn exceeds the capacity of the lead wire, it melts from the heat, and thus opens the circuit, and cuts off the current. Items of Cost This water wheel would cost $250 new. There is a duplicate in the neighbor- hood bought at second-hand, for $125. The A switchboard and its connections: G. Dyna- mo; A. Shunt field coils; B. Series coils; DD. Fuses; FF. Main switch; F. Field switch; C. Ammeter; V. Volt- meter; E. Lamp; R. Rheostat. Dotted lines show connections on back of board 132 ELECTRICITY FOR THE FARM dynamo cost $90, and was picked up second- hand in New York City. New it would cost $150. The voltmeter cost $7, and the ammeter $10; and the switches and fuses could be had for $5. A wheel one-half the size, using one- half the amount of water at full gate, would do the work required, and the cost would be correspondingly less. Capacity This plant supplies two farms with electric light. One farm (that of the owner of the wheel) has 30 lamps, of 16 candlepower each, and two barn-yard lamps of 92 candlepower each. His wife has an electric iron and an electric water heater. Needless to say, all these lamps, and the iron and water heater are not in use at one time. The partner who owns the electric part of the plant has 30 lamps in his house and barn, Carbon Lamps Gem Type (% scale) WHAT SIZE PLANT TO INSTALL 133 many of them being 25 watt tungsten, which give more light for less power, but cost more to buy. They are not all in use at one time, though (since the current costs nothing) the inclination is to turn them on at night and let them burn. In his kitchen he has an electric range, and a water heater for the 40 gallon boiler. In addition to this he has all sorts of appliances, irons, toasters, grills, a vacuum cleaner, a vibrator, etc. Naturally all these appliances are not in use at one time, else the draft on the plant would be such as to "blow " the fuses. For instance, all the baking is done in daylight; and when the oven is used after dark, they are careful to turn off all lights not needed. An 'ideal plant, of course, would be a plant big enough to take care of the sum of lamps and handy devices used at one time. To make this plant ideal, (for, being an actual affair, it has developed some short- comings, with the extension of the use of elec- tricity) it would require a dynamo whose capacity can be figured, from the following: 134 ELECTRICITY FOR THE FARM Watts 15 carbon lamps, 16 candlepower, @60 watts each 900 10 tungsten lamps, 20 candlepower, @25 watts each 250 2 tungsten lamps, 92 candlepower, @100 watts each ....... 200 Water heater, continuous service 800 Toaster, occasional service 600 Iron, occasional service 400 Oven-baking, roasting, etc 2,000 2 stove plates @1,000 watts each 2,000 1 stove plate 400 Vacuum cleaner, occasional service 200 Vibrator, occasional service 100 Small water heater, quart capacity 400 Small motor, % horsepower, occasional 250 Motor, % n P pumping water, etc 500 Electric fan, occasional service 100 Total current, one house 9,100 30 carbon lamps, 16 candlepower, @60 1,800 2 lamps, 100 watt tungsten 200 Electric iron 400 Small water or milk heater 600 Total current, 2nd house 3,000 1st house.. 9,100 12,100 Thus, in this plant, if every electrical device were turned on at once, the demand on the dynamo would be for 12.1 kilowatts, or an overload of over 100 per cent. The main- switch fuse, being for 60 amperes, would "blow" or melt, and cut off all current for the WHAT SIZE PLANT TO INSTALL 135 moment. To repair the damage would be merely the work of a second and at a cost of a few cents simply insert a new fuse, of which there must be a supply on hand at all times . Or, if either owner exceeded his capacity, the line fuses (one for 20 25 and 40 watt Mazda tung- amperes, and the other sten lamps (^ scale) for 40 amperes) would instantly cut off all cur- rent from the greedy one. Lessons From This Plant The story of this plant illustrates two things which the farmer and his wife must take into account when they are figuring how much electricity they require. First, it illustrates how one uses more and more current, as he finds it so serviceable and labor-saving, and at the same time free. The electric range and the water boiler, in the above instance, were later acquisitions not counted on in figuring the original installation. Second, it illustrates, 136 ELECTRICITY FOR THE FARM that while the normal load of this generator is 5.75 kilowatts, one does not have to limit the electrical conveniences in the home to this amount. True, he cannot use more electricity than his plant will produce at any one time, but it is only by a stretch of the imagination that one may conceive the necessity of using them all at once. Ironing, baking, and the use of small power are usually limited to daylight hours when no lights are burning. As a matter of fact, this plant has proved satisfactory in every way; and only on one or two occasions have fuses been "blown", and then it was due to carelessness. A modern dynamo is rated liberally. It will stand an overload of as much as 100 per cent for a short time half an hour or so. The danger from overloading is from heating. When the machine grows too hot for the hand, it is beginning to char its insulation, to continue which, of course would ruin it. The best plant is that which works under one-half or three-quarters load, under normal de- mands. WHAT SIZE PLANT TO INSTALL 137 Standard Voltage We are assuming the farmer's plant to be, in 99 cases out of 100, the standard 110-volt, direct current type. Such a plant allows for at least a 10 per cent regulation, in voltage, up or down the scale; supplies for this voltage are to be had without delay in even the more remote parts of the country, and (being sold in greater volume) they are cheaper than those for other voltages. There are two general exceptions to this rule as to 110-volt plants: (1) If the plant is located at a distance greater than a quarter of a mile from the house, it will be found cheaper (in cost of transmission line, as will be shown later) to adopt the 220-volt plant; (2), If the water supply is so meagre that it must be stored for many hours at a time, and then used for charging storage batteries, it will be found most economical to use a 30-volt plant. A storage battery is made up of cells of approximately 2 volts each; and, since more than 55 such cells would be required for a 138 ELECTRICITY FOR THE FARM 110-volt installation, its cost would be pro- hibitive, with many farmers. So we will assume that this plant is a 110- volt plant, to be run without storage battery. It will be well to make a chart, dividing the farm requirements into three heads light, heat, and power. Light Light is obtained by means of incandescent lamps. There are two styles in common use, 60 and 100 watt Mazda tungsten lamp. These lamps may be had in sizes from 10 to 500 watts (% scale) the carbon and the tungsten lamp. It requires 3.5 to 4 watts of electricity to produce one candlepower in a carbon lamp. It requires WHAT SIZE PLANT TO INSTALL 139 from 1 to 1.25 watt to produce one candlepower in the tungsten lamp. The new nitrogen lamp, not yet in general use, requires only J^ watt to the candlepower. Since tungsten lamps give three times the light of the carbon lamp, they are the most economical to use in the city or town where one is paying for commer- cial current. But, in the country where water-powerfurnishes current for nothing, it will be found most economical to use the carbon lamp, since its The lamp of the future. A 1000 COSt at retail IS 16 wa tt Mazda nitrogen lamp, giving CentS, as Compared 000 candlepower (M scale) with 30 cents for a corresponding size in tung- sten. A 60 watt carbon lamp, of 16 candle- power; or a 25 watt tungsten lamp, of 20 140 ELECTRICITY FOR THE FARM candlepower, are the sizes to use. In hang- ing lamps, as over the dining room table, a 100 watt tungsten lamp, costing 70 cents, and giving 92 candlepower light is very de- sirable; and for lighting the barn-yard, these 100 watt tungsten lamps should be used. For reading lamps, the tungsten style, of 40 or 60 watt capacity, will be found best. Other- wise, in all locations use the cheaper carbon lamp. Both styles have a rated life of 1,000 hours, after which they begin to fall off in efficiency. Here again, the farmer need not worry over lack of highest efficiency, as a lamp giving only 80 per cent of its rated candlepower is still serviceable when he is not paying for the current. With care not to use them at voltages beyond their ratings, lamps will last for years. A Specimen Light Allowance Below is a typical table of lights for a large farm house, the barns and barn -yard. It is given merely as a guide, to be varied for each individual case: WHAT SIZE PLANT TO INSTALL 141 Watts Kitchen, 2 lights @60 watts 120 Dining room, 1 light, tungsten 100 Living room, table lamp with 3 tungstens @40 120 Living room, 2 wall fixtures, 4 lamps @60 watts 240 Parlor, same as living room 360 Pantry, 1 hanging lamp 60 Cellar, one portable lamp 60 Woodshed, 1 hanging lamp 60 2 bedrooms, 2 lights each @ 60 240 2 bed rooms, 1 light each @60 120 Bathroom, 1 "turn-down" light, @60 60 Hall, downstairs, 2 lights @60 120 Hall, upstairs, 1 light 60 Attic, 1 light 60 Porch, 1 light 60 Bam and barn-yard: Barn-yard entrance, 1 tungsten 100 Watering trough, 1 " 100 Front gate, 1 " 100 Horse bam, 4 lights @60 240 Cow barn, 4 lights @60 240 Pig house, 1 light 60 Hay bam, 2 lights, @60 120 Total for farmstead 2,800 This provides for 44 lights, an extremely liberal allowance. How many of these lights will be burning at any one time? Probably not one-half of them; yet the ideal plant is that w r hich permits all fixtures to be in serv- ice at one time on the rare occasions when necessary. Thus, for lighting only, 2,800 142 ELECTRICITY FOR THE FARM watts maximum service would require a 4 kilowatt generator, and 10 water horse- power, on the liberal rating of two to one. A 3 kilowatt generator would take care of these lights, with a 30 per cent overload (which is not excessive) for maximum service. The above liberal allowance of lights may be cut in two, or four or even eight and still throw a kerosene lamp in shadow. It all depends on the number of lights one wants burning at one time; and the power of the water wheel. If the 36 carbon lights in the above table were replaced by 25 watt tungsten lights, the saving in power would be 35 watts each, or 1,260 watts, nearly two electrical horse- power; while the added first cost would be 14 cents a light, or $5.04. A generator of 2 kilowatt capacity would take care of all these lights then, with 460 watts to spare. Heating Electric heating and cooking is in its in- fancy, due to the prohibitive cost of com- WHAT SIZE PLANT TO INSTALL 143 mercial current in our cities. Here the far- mer has the advantage again, with his cheap current. For heating the house, it is calculated that 2 watts is required for each cubic foot of air space in a room, during ordinary winter weather. Thus, a room 10 x 12, and 8 feet high, would contain 960 cubic feet, and would require 1,820 watts energy to heat it in cold weather. Five such rooms would require 9.1 kilowatts; and 10 such rooms, or their equivalent, would require 18.2 kilowatts. Electric heating devices are divided into two classes: (1) those which can be used on lamp circuits, and do not draw more than 660 watts each; and (2) those which draw more than 660, therefore require special wiring. The capacity of these devices is approximately as follows: Lamp circuit devices: Watts Electric iron 400 to 660 Toaster 350 to 660 Vacuum cleaner 200 to 400 Grill 400 to 660 Small water heater 400 to 660 Hot plates 400 to 660 144 ELECTRICITY FOR THE FARM Lamp circuit devices: Watts Coffee percolator 400 to 660 Chafing dish 400 to 660 Electric fan 100 to 250 Special circuit devices: Hot water boiler heater 800 to 1,200 Small ovens 660 to 1,200 Range ovens 1,200 to 3,000 Range, hot plates 400 to 1,300 Radiators (small) 750 to 1,500 Radiators( large) 1,500 to 6,000 The only device in the above list which is connected continuously, is the hot water boiler, and this can be credited with at least one electrical horsepower 24 hours a day. It is a small contrivance, not much bigger than a quart can, attached to the back of the kitchen boiler, and it keeps the water hot throughout the house at all hours. Its cost will vary with the make, ranging from $8 to $15; and since it is one of the real bless- ings of the farm kitchen and bathroom, it should be included in all installations where power permits. Electric radiators will be used 24 hours a day in winter, and not at all in summer. They are portable, and can WHAT SIZE PLANT TO INSTALL 145 be moved from room to room, and only such rooms as are in actual use need be heated. The other devices are for intermittent serv- ice, many of them (like the iron) for only a few hours each week. The grill, chafing dish, coffee percolator, etc., which are used on the dining room table while the family is at meals, each draw an equivalent of from 6 to 10 carbon lights. By keeping this in view and turning off spare lights, one can have the use of them, with even a small plant. Thus, a one kilowatt plant permits the use of any one of these lamp circuit devices at a time, with a few lights in addition. Power Electric power is to be had through motors. A direct current dynamo and a direct current motor are identical in construction. That is, a motor becomes a generator if belted to power; and a generator becomes a motor, if connected to electric mains. This is best illustrated by citing the instance of a trans-continental 146 ELECTRICITY FOR THE FARM Main Connections of shunt motor and starting rheostat railroad which crosses the Bitter Root Moun- tains by means of electric power. Running 200 miles up a 2 per cent grade, it is drawn WHAT SIZE PLANT TO INSTALL 147 by its motors. Coasting 200 miles down the 2 per cent grade on the other side of the moun- tains, its motors become generators. They act as brakes, and at the same time they pump the power of the coasting weight of this train back into the wires to help a train coming up the other side of the moun- tains. Just as there are three types of direct cur- rent generators, so there are three types of direct current motors: series, shunt, and compound, with features already explained in the case of generators. Motors are rated by horsepower, and generators are rated by kilowatts. Thus a one kilowatt generator has a capacity of 1,000 watts; as a motor, it would be rated as *f- horsepower, or 1.34 horsepower. Their efficiency varies with their size, ranging from 40 to 60 per cent in very small motors, and up to 95 per cent in very large ones. The following table may be taken as a guide in calculating the power required by motors, on 110-volt cir- cuits: 148 ELECTRICITY FOR THE FARM 34 Horsepower 2^ amperes, or 275 watts ]/2 hp 4^ amperes, or' 500 watts 1 hp 9 amperes, or 990 watts 2 hp 17 amperes, or 1 . 97 kilowatts 3 hp 26 amperes, or 2 . 86 kilowatts 5 hp 40 amperes, or 4 . 40 kilowatts 73^ hp 60 amperes, or 6 . 60 kilowatts 10 hp 76 amperes, or 8 . 36 kilowatts 15 hp 112 amperes, or 12.32 kilowatts An electric motor, in operation, actually generates electricity, which it pushes back into the line as a counter-electromotive-force. The strength of this counter force, in volts, depends on the motor's speed, the same as if it were running as a dynamo. For this reason, when a motor is started, and before it comes up to speed, there would be a rush of current from the line, with nothing to hold it back, and the motor would be burned out unless some means were provided to protect it for the moment. This is done by means of a starting rheostat, similar to the regulating rheostat on the dynamo switchboard. This resistance box is connected in "series" with the armature, in the case of shunt and compound motors; and with the entire WHAT SIZE PLANT TO INSTALL 149 motor circuit in the case of a series ma- chine. A series motor has a powerful starting torque, and adjusts its speed to the load. It is used almost altogether in street cars. It can be used in stump pulling, or derrick work, such as using a hay fork. It must al- ways be operated under load, otherwise, it would increase in speed until it tore itself to pieces through mechanical strain. The ingenious farmer who puts together an elec- tric plow, with the mains following behind on a reel, will use a series motor. A shunt motor should be used in all situa- tions where a fairly uniform speed under load is required, such as separating, in milk- ing machines, running a lathe, an ensilage cutter, vacuum cleaners, grinders, etc. The compound motor has the characteristics of the series and shunt motors, giving an increased starting torque, and a more nearly constant speed under varying loads than the shunt motor, since the latter drops off slightly in speed with increasing load. 150 ELECTRICITY FOR THE FARM Flexible Power An electric motor is an extremely satisfac- tory form of power because it is so flexible. Thus, one may use a five horsepower motor for a one horsepower task, and the motor will use only one electrical horsepower in current just enough to overcome the task imposed on it. For this reason, a large-sized motor may be used for any operation, from one requiring small power, up to its full capacity. It will take an overload, the same as a dynamo. In other words it is "eager" for any task imposed on it; therefore it must be protected by fuses, or it will consume itself, if too big an overload is imposed on it. A one horsepower shunt or compound motor is very serviceable for routine farm operations, such as operating the separator, the churn, the milking machine, grinder, pump, and other small power jobs. Motors of J4 horsepower are handy in the kitchen, for grinding knives, polishing silver, etc., and can be used also for vacuum cleaners, and running the sewing WHAT SIZE PLANT TO INSTALL 151 machine. For the larger operations, motors will vary from three horsepower for cutting ensilage, to fifteen horsepower for threshing. They can be mounted on trucks and conveyed from one point to another, being fed current from the mains by means of suitable wires wound on reels. Remember, in estimating the size of your plant for light, heat, and power, that it does not have to be big enough to use all the devices at one time. Also remember, that two water horsepower to one electrical horsepower is a very liberal allowance; and that a generator working under one-half or two-thirds capacity at normal loads will require less attention than a machine constantly being worked above its capacity. Therefore, let your generator be of liberal size, because the differ- ence in cost between a 5 and 10 kilowatt machine is not in proportion to their capacity. In fact (especially among second-hand ma- chines), the difference in cost is very small. The mere fact that the generator is of 110 electrical horsepower capacity does not require 152 ELECTRICITY FOR THE FARM a turbine of 20 horsepower. The chances are that (unless you wish to heat your house and do large power jobs) you will not use more than 3 to 5 electrical horsepower normally; therefore an allowance of 10 water horsepower, in this case, would be ample. A plant used simply for lighting the house and barn, for irons, and toasters, and one horsepower motors, need not exceed 2 or 2 1/2 kilowatts for the generator, and 5 or 6 horsepower for the turbine wheel. Normally it would not use one-half this capacity. CHAPTER VII TRANSMISSION LINES Copper wire Setting of poles Loss of power in trans- mission Ohm's Law and examples of how it is used in figuring size of wire Copper- wire tables Examples of transmission lines When to use high voltages Over-compounding a dynamo to overcome transmission loss. HAVING determined on the location of the farm water-power electric plant, and its capac- ity, in terms of electricity, there remains the wiring, for the transmission line, and the house and barn. For transmission lines, copper wire covered with waterproof braid the so-called weather- proof wire of the trade is used. Under no circumstances should a wire smaller than No. 8, B. & S. gauge be used for this purpose, as it would not be strong enough mechanically. The poles should be of chestnut or cedar, 25 feet long, and set four feet in the ground. Where it is necessary to follow highways, they 153 154 ELECTRICITY FOR THE FARM should be set on the fence line; and in crossing public highways, the ordinance of your own town must guide you. Some towns prescribe a height of 19 feet above the road, others 27 feet, some 30. Direct current, such as is advised for farm installations, under ordinary circumstances, does not affect telephone wires, and therefore transmission lines may be strung on telephone poles. Poles are set at an average distance of 8 rods; they are set in- clined outward on corners. Sometimes it is necessary to brace them with guy wires or wooden braces. Glass insulators are used to fasten the wires to the cross-arms of the poles, and the tie-wires used for this purpose must be the same size as the main wire and carry the same insulation. Size of Wire for Transmission To determine the size of the transmission wires will require knowledge of the strength of current (in amperes) to be carried, and the distance in feet. In transmission, the electric current is again analogous to water flowing in TRANSMISSION LINES 155 pipes. It is subject to resistance, which cuts down the amount of current (in watts) deliv- ered. The loss in transmission is primarily meas- ured in volts; and since the capacity of an electric current for work equals the volts A~ GLA&S INSULATOR, 3~ Z>AZP LOOP C EffTRAATGE ^SWITCH D~ SWITCH KfiNEL FOR. HOUSE SE&I/7CE E - PORCELAIN TUBE& F~FUSB PLUG* Bringing wires into the house or barn multiplied by amperes, which gives watts, every volt lost reduces the working capacity of the current by so much. This loss is referred to by electrical engineers as the "C 2 R loss," which is another way of saying that the loss is equal to the square of the current in amperes, multiplied by ohms resistance. Thus, if the 156 ELECTRICITY FOR THE FARM amperes carried is 10, and the ohms resistance of the line is 5, then the loss in watts to convey that current would be (10 x 10) x 5, or 500 watts, nearly a horsepower. The pressure of one volt (as we have seen in another chapter) is sufficient to force one ampere, through a resistance of one ohm. Such a current would have no capacity for work, since its pressure would be consumed iix the mere act of transmission. If, however, the pressure were 110 volts, and the current one ampere, and the resistance one ohm, the effective pressure after transmis- sion would be 110 1, or 109 volts. To force a 110-volt current of 50 amperes through the resistance of one ohm, would re- quire the expenditure of 50 volts pressure. Its capacity for work, after transmission, would be 11050, or 60 volts, x 50 amperes, or 3,000 watts. As this current consisted of 110 x 50, or 5,500 watts at the point of starting, the loss would be 2,500 watts, or about 45 per cent. It is bad engineering to allow more than 10 per cent loss in transmission. TRANSMISSION LINES 157 There are two ways of keeping this loss down. One is by increasing the size of the transmission wires, thus cutting down the resistance in ohms; the other way is by raising the voltage, thus cutting down the per cent loss. For instance, suppose the pressure was 1,100 volts, instead of 110 volts. Five amperes at 1,100 volts pressure, gives the same number of watts, power, as 50 amperes, at 110 volts pressure. Therefore it would be necessary to carry only 5 amperes, at this rate. The loss would be 5 volts, or less than ^ of 1 per cent, as compared with 45 per cent with 110 volts. In large generating stations, where individ- ual dynamos frequently generate as much as 20,000 horsepower, ==^SSSssss3&2>=s and the Current must Splicing transmission wire be transmitted over several hundred miles of territory, the voltage is frequently as high as 150,000, with the amperes reduced in propor- tion. Then the voltage is lowered to a suitable rate, and the amperage raised in proportion, by special machinery, at the point of use. It is the principle of the C 2 R loss, which the 158 ELECTRICITY FOR THE FARM farmer must apply in determining the size of wire he is to use in transmitting his current from the generator switchboard to his house or barn. The wire table on page 159, together with the formula to be used in connection with it, reduce the calculations necessary to simple arithmetic. In this table the resistance of the various sizes of wire is computed from the fact that a wire of pure copper 1 foot long, and 1/1000 inch in diameter (equal to one circular mill) offers a resistance of 10.6 ohms to the foot. The principle of the C 2 R loss is founded on Ohm's Law, which is explained in Chapter V. The formula by which the size of trans- mission wire is determined, for any given distance, and a given number of amperes, is as follows: Distance ft. one way x %% x No. of amperes _ circular Number of volts lost mills. In other words, multiply the distance in feet from mill to house by 22, and multiply this product by the number of amperes to be COPPER WIRE TABLE B. &S. Gauge Feet per Lb. Area in circular mills (R) Ohms per 1,000 feet Feet per Ohm (R) Ohms per pound 0000 1.561 211,600 .04904 20,392.90 .00007653 000 1.969 167,805 .06184 16,172.10 .00012169 00 2.482 133,079 .07797 12,825.40 .00019438 3.130 105,534 .09829 10,176.40 .00030734 1 3.947 83,694 . 12398 8,066.00 .00048920 2 4.977 66,373 . 15633 6,396.70 .00077784 3 6.276 52,634 .19714 5,072.50 .00123700 4 7.914 41,742 .24858 4,022.90 .00196660 5 9.980 33,102 .31346 3,190.20 .00312730 6 12.58 26,250 .39528 2,529.90 .00497280 7 15.87 20,816 .49845 2,006.20 .00790780 8 20.01 16,509 .62840 1,591.10 .01257190 9 25.23 13,094 .79242 1,262.00 . 01998530 10 31.82 10,381 .99948 1,000.50 .03178460 11 40.12 8,234.0 1 26020 793.56 .05054130 12 50.59 6,529.9 1.58900 629.32 .08036410 13 63.79 5,178.4 2.00370 499.06 . 12778800 14 80.44 4,106.8 2.52660 395.79 .20318000 15 101.4 3,256.7 3.18600 313.87 .32307900 16 127.9 2,582.9 4.01760 248.90 .51373700 17 161.3 2,048.2 5.06600 197.39 .81683900 18 203.4 1,624.3 6.38800 156.54 1.29876400 CARRYING CAPACITY OF WIRES AND WEIGHT B. &S. Gauge No. Weight 1,000 //. Weatherproof (Pounds) Carrying capacity Weatherproof (Amperes) Carrying capacity rubber cov. (Amperes) 0000 800 312 175 000 666 262 145 00 500 220 120 363 185 100 1 313 156 95 2 250 131 70 3 200 110 60 4 144 92 50 5 125 77 45 6 105 65 85 7 87 55 30 8 69 46 25 10 50 32 20 12 31 23 15 14 22 16 10 16 14 8 5 18 11 5 3 159 160 ELECTRICITY FOR THE FARM carried. Then divide the product by the number of volts to be lost; and the result will be the diameter of the wire required in circu- lar mills. By referring to the table above, the B. & S. gauge of the wire necessary for transmission, can be found from the nearest corresponding number under the second col- umn, entitled "circular mills area." Since two wires are required for electrical transmission, the above formula is made simple by counting the distance only one way, in feet, and doubling the resistance constant, 10.6, which, for convenience is taken as 22, instead of 21.2. Examples of Transmission Lines As an example, let us say that Farmer Jones has installed a water-power electric plant on his brook, 200 yards distant from his house. The generator is a 5 kilowatt machine, capable of producing 1+5 amperes at 110 volts pressure. He has a 3 horsepower motor, drawing 26 amperes at full load; he has 20 lights of varying capacities, requiring TRANSMISSION LINES 161 1,200 watts, or 10 amperes when all on; and his wife uses irons, toasters, etc., which amount to another 9 or 10 amperes say 45 altogether. The chances are that he will never use all of the apparatus at one time; but for flexi- bility, and his own satisfaction in not having to stop to think if he is overloading his wires, Transmission wire on glass insulator he would like to be able to draw the full 1*5 amperes if he wishes to. He is willing to allow 5 per cent loss in transmission. What size wires will be necessary, and what will they cost? Substituting these values in the above formula, the result is: Answer: 600 x 22 x 45 , AOAnrt . , . = 108,000 circular mills. o.o Referring to the table, No. wire is 105,534 circular mills, and is near enough; so this wire would be used. It would require 1,200 feet, 162 ELECTRICITY FOR THE FARM which would weigh, by the second table, 435.6 pounds. At 19 cents a pound, it would cost $82.76. Farmer Jones says this is more money than he cares to spend for transmission. As a matter of fact, he says, he never uses his motor except in the daytime, when his lights are not burning; so the maximum load on his line at any one time would be 26 amperes, not 45. What size wire would he use in this instance? Substituting 26 for 45 in the equation, the result is 61,300 circular mills, which corre- sponds to No. 2 wire. It would cost $57.00. Now, if Farmer Jones, in an emergency, wished to use his motor at the same time he was using all his lights and his wife was iron- ing and making toast in other words, if he wanted to use the 45 amperes capacity of his dynamo, how many volts would he lose? To get this answer, we change the formula about, until it reads as follows: Distance in feet x 22 x amperes XT , . , , -. i TH = Number of volts lost circular mills TRANSMISSION LINES 163 Substituting values, we have, in this case, 600 x 22x45 66,373 (No. 2) = 9 V ltS ' nearly ' leSS th&n 10 per cent. This is a very efficient line, under the circumstances. Now if he is willing to lose 10 per cent on half -load, instead of full load, he can save still more money in line wire. In that case (as you can find by applying the formula again), he could use No. 5 wire, at a cost of $28.50. He would lose 11 volts pres- sure drawing 26 amperes; and he would lose 18 volts pressure drawing 45 amperes, if by any chance he wished to use full load. In actual practice, this dynamo would be regulated, by means of the field resistance, to register 110 plus 11 volts, or 121 volts at the switchboard to make up for the loss at half -load. At full load, his voltage at the end of the line would be 121 minus 18, or 103 volts; his motor would run a shade slower, at this voltage, and his lights would be slightly dimmer. He would probably not notice the difference. If he did, he could walk over to his generating station, and raise 164 ELECTRICITY FOR THE FARM the voltage a further 7 volts by turning the rheostat handle another notch. Thousands of plants can be located within 100 feet of the house. If Farmer Jones could do this, he could use No. 8 wire, costing $2.62. The drop in pressure would be 5.99 volts at full load so small it could be ig- nored entirely. In this case the voltmeter should be made to read 116 volts at the switchboard, by means A barn-yard light , , or the rheostat. If, on the other hand, this plant were 1,000 feet away from the house and the loss 10 volts 1,000 x 22 x 45 the size wire would be 10 99,000 circular mills; a No. wire comes nearest to this figure, and its cost, for 2,000 feet, at 19 cents a pound, would be $137.94. TRANSMISSION LINES 165 A No. 0000 wire, costing $294.00, would give a 5 per cent drop at full load. In this case, the cost of transmission can be reduced to a much lower figure, by allowing a bigger drop at half-load, with regulation at the switch- board. Thus, a No. 2 wire here, costing but $95, would be satisfactory in every way. The loss at half-load would be about 9 volts, and the rheostat would be set permanently for 119 or 120 volts. A modern dynamo can be regulated in voltage by over 25 per cent in either direction, without harm, if care is taken not to overload it. Benefit of Higher Voltages If Farmer Jones' plant is a half of a mile away from the house, he faces a more serious proposition in the way of transmission. Say he wishes to transmit 26 amperes with a loss of 10 volts. What size wire will be necessary? 2640 x 22 x 26 Thus: -JQ - = 151,000 circular mills. A No. 000 wire is nearest this size, and 5,280 feet of it would cost over $650.00. This cost 166 ELECTRICITY FOR THE FARM would be prohibitive. If, however, he in- stalled a 220-volt dynamo at no increase in cost then he would have to transmit only a half of 26 amperes, or 13 amperes, and he could allow 22 volts loss, counting 10 per cent. In this case, the problem would work out as follows: 2640 x 22 x 13 Q . QOA . , . - = 34,320 circular mills, or ap- proximately a No. 5 w r ire which, at 19 cents a pound, would cost $120.65. Install a 550-volt generator, instead of a 220-volt machine and the amperes necessary would be cut to 5.2, and the volts lost would be raised to 55. In this case a No. 12 wire would carry the current; but since it would not be strong enough for stringing on poles, a No. 8 wire would be used, costing about $63. It will be readily seen from these examples how voltage influences the efficiency of trans- mission. Current generated at a pressure in excess of 550 volts is not to be recommended for farm plants unless an expert is in charge. TRANSMISSION LINES 167 A safer rule is not to exceed 220 volts, for while 550 volts is not necessarily deadly, it is dangerous. When one goes into higher volt- ages, it is necessary to change the type of dynamo to alternating current, so that the current can be transformed to safe voltages at the point where it is used. Since only the occasional farm plant requires a high-tension system, the details of such a plant will not be gone into here. In transmitting the electric current over miles of territory, engineers are accustomed to figure 1,000 volts for each mile. Since this is a deadly pressure, it should not be handled by any one not an expert, which, in this case, the farmer is not. Over -Compounding the Generator One can absorb the loss in transmission fre- quently, by over-compounding the machine. In describing the compound machine, in Chapter Five, it is shown that the usual com- pound dynamo on the market is the so-called flat-compounded type. In such a dynamo, the 168 ELECTRICITY FOR THE FARM voltage remains constant at the switchboard, from no load to full load, allowing for a slight curve which need not be taken into account. Now, by adding a few more turns to the series wires on the field coils of such a dynamo, a machine is to be had which gradually raises its voltage as the load comes on in increasing volume. Thus, one could secure such a ma- chine, which would begin generating at 110 volts, and would gradually rise to 150 at full load. Yet the voltage would remain constant at the point of use, the excess being absorbed in transmission. A machine of this type can be made to respond to any required rise in voltage. As an example of how to take advantage of this very valuable fact, let us take an in- stance: Say that Farmer Jones has a transmission line 1,000 feet long strung with No. 7 copper wire. This 2,000 feet of wire would introduce a resistance of one ohm in the circuit. That is, every ampere of current drawn at his house would cause the working voltage there to fall TRANSMISSION LINES 169 one volt. If he drew 26 amperes, the voltage would fall, at the house, 26 volts. If his switchboard voltage was set ; at say 120, the voltage at his house, at 26 amperes of load, would fall to 94 volts, which would cause his lights to dim considerably. It would be a very unsatisfactory transmission line, with a flat- compounded dynamo. On the other hand, if his dynamo was over- compounded 25 per cent that is, if it gained 28 volts from no load to full load, the system would be perfect. In this case, the dynamo would be operated at 110 volts pressure at the switchboard with no load. At full load the voltmeter would indicate 110 plus 26, or 136 volts. The one or two lights burned at the power plant would be subject to a severe strain; but the 50 or 100 lights burned at the house and barn would burn at constant volt- age, which is very economical for lamps. The task of over-compounding a dynamo can be done by any trained electrician. The farmer himself, if he progresses far enough in his study of electricity, can do it. It is neces- 170 ELECTRICITY FOR THE FARM sary to remove the top or "series" winding from the field coils. Count the number of turns of this wire to each spool. Then procure some identical wire in town and begin experi- menting. Say you found four turns of field wire to each spool. Now wind on five, or six, being careful to wind it in the same direction as the coils you removed and connect it in the same way. If this additional number of turns does not raise the voltage enough, in actual practice, when the dynamo is running from no load to full load, add another turn or two. With patience, the task can be done by any careful mechanic. The danger is in not winding the coils the same way as before, and getting the connections wrong. To prevent this mistake, make a chart of the " series " coils as you take them off. To make the task of over-compounding your own dynamo even more simple, write to the manufacturers, giving style and factory number of your machine. Tell them how much voltage rise you wish to secure, and ask them how many turns of "series" wire should TRANSMISSION LINES 171 be wound on each spool in place of the old "series" coil. They could tell you exactly, since they have mathematical diagrams of each machine they make. Avoid overloading an over-compounded ma- chine. Since its voltage is raised automat- ically, its output in watts is increased a similar amount at the switchboard, and, for a given resistance, its output in amperes would be increased the same amount, as can be ascer- tained by applying Ohm's Law. Your ammeter is the best guide. Your machine is built to stand a certain number of amperes, and this should not be exceeded in general practice. CHAPTER VIII WIRING THE HOUSE The insurance code Different kinds of wiring de- scribed Wooden moulding cheap and effective The distributing panel Branch circuits Pro- tecting the circuits The use of porcelain tubes and other insulating devices Putting up chande- liers and wall brackets "Multiple" connec- tions How to connect a wall switch Special wiring required for heat and power circuits Knob and cleat wiring, its advantages and draw- backs. THE task of wiring your house is a simple one, with well-defined rules prescribed by your insurance company. Electricity, properly in- stalled, is much safer than oil lamps so much so indeed that insurance companies are ready to quote especial rates. But they re- quire that the wiring be done in accordance with rules laid down by their experts, who form a powerful organization known as the National Board of Fire Underwriters. Ask your in- surance agent for a copy of the code rules. 172 WIRING THE HOUSE 173 Danger of fire from an electric current comes from the "short circuit," partial or complete; and it is against this danger that the rules guard one. The amount of electricity flowing through a short circuit is limited only by the fuse protecting that line; and since there is no substance known that can with- stand the heat of the electric arc, short circuits must be guarded against. Happily the current is so easily controlled that the fire hazard is eliminated entirely something which cannot be done with oil lamps. In house-wiring for farm plants, the wire should be rubber-covered, and not smaller than No. 14 B. & S. gauge. This is the wire to use on all lamp circuits. It costs about $0.85 cents per 100 feet. There are four kinds of wiring permitted, under the insurance code: (1) Flexible armoured cable: This consists of two-wire cable, protected with a covering of flexible steel. It is installed out of sight between the walls, and provides suitable out- lets for lamps, etc., by means of metal boxes 174 ELECTRICITY FOR THE FARM set flush with the plaster. It is easily installed in a house being built, but requires much tearing down of plaster for an old house. Since its expense prohibits it in the average farm house, this system will not be described in detail here. (2) Rigid and flexible conduit: As the name implies this system consists of iron pipe, in connection with flexible conduit, run between the walls. It differs from the above system, in that the pipes with their fittings and outlet boxes are installed first, and the wires are then "fished" through them. Duplex wires the two wires of the circuit woven in one braid are used; and a liberal amount of soapstone, and occasionally kerosene, are used to make the wires slip easily into place. This is the most expensive system, and the best; but it is difficult to install it in an old house without tearing down a good deal of plaster. It has the advantage of being absolutely waterproof and fire- proof. WIRING THE HOUSE 175 (3) Wooden moulding: This is simply mould- ing, providing two raceways for the insulated wires to run in, and covered with a capping. It is nailed or screwed firmly to the wall, on top of the plaster; and when the wires have been installed in their respec- tive slots and the capping tacked on, the moulding is given a COat of paint to DetaU of wooden moulding make it in harmony with the other moulding in the room. This system is cheap, safe, and easily installed, and will be described in detail here. (4) Open wiring: In open wiring, the wires are stretched from one support to another (such as beams) and held by means of porce- lain cleats, or knobs. It is the simplest to install; but it has the objection of leaving the wires unprotected, and is ugly. It is very satisfactory hi barns or out-buildings how- ever. 176 ELECTRICITY FOR THE FARM The Distributing Panel The first point to consider in wiring a house with wooden moulding is the distribution board.. It should be located centrally, on the wall near the ceiling, so as to be out of ordinary reach. It consists of a panel of wood though fireproof material is better firmly screwed to the wall, and contain- ing in a row, the por- c e 1 a i n cut-outs, as shown in the cut, from Porcelain cut-out and plug fuse ^^ f >^ v a T i O U S branch circuits are to be led. Each cut- out provides for two branch circuits; and each branch contains receptacles for two plug fuses. These fuses should be of 6 amperes each. The Insurance Code limits the amount of electricity that may be drawn on any branch lamp circuit to 660 watts; and these fuses protect the circuit from drafts beyond this amount. The mains, leading from the entrance switch, as shown in the diagram, to the panel WIRING THE HOUSE 177 board, should be of the same size as the trans- mission wire itself, and rubber-covered. These mains terminate at the distributing board. They are connected to the terminals of the cut-outs by means of heavy brass screws. Wire Joints The branch circuits are, as has been said, of No. 14 rubber-covered wire, running con- Examples of cleat and knob wiring, 1, 2, 3; wire joints, 4; flexible armoured conductor, 5 cealed in wooden moulding. All joints or splices in this wire are made, as shown in the illustration, by first scraping the wires bright, and fastening them stoutly together. This joint is then soldered, to make the connection electrically perfect. Soft solder is used, with 178 ELECTRICITY FOR THE FARM ordinary soldering salts. There are several compounds on the market, consisting of soft solder in powder form, ready-mixed with flux. Coat the wire joint with this paste and apply the flame of an alcohol lamp. The soldered joint is then covered with rubber tape, and over this ordinary friction tape is wound on. A neat joint should not be larger than the diameter of the wire before insulation is re- moved. Branch Circuits First, make a diagram of your rooms and indicate where you wish lamps, or outlets for other purposes. Since wooden moulding can be run across ceilings, and up or down walls, lamps may be located in places where they are out of the way. In planning the circuit, remember that you will want many outlets in handy places on the walls, from which portable cords will convey current to table lamps, to electric irons and toasters and other handy devices which can be used on the lamp circuit. These outlets are made of porcelain, WIRING THE HOUSE 179 in two pieces. One piece is merely a continua- tion of the moulding itself; and the other is a cap to connect permanently te the end of the lamp or iron cord, which may be snapped into place in a second. Since there are a great many designs of separable current taps on the market, it is well to select one design and stick to it throughout the house, so that any device can be connected to any outlet. The code permits 660 watts on each circuit. This would allow 12 lamps of 55 watts each. It is well to limit any one circuit to 6 lamps; this will give leeway for the use of small stoves, irons, toasters, etc. without overloading the circuit and causing a fuse to blow. Having installed your distributing board, with its cut-outs, figure out the course of your first branch circuit. Let us say it will provide lights and outlets for the dining room and living room. It will be necessary to run the wires through the partitions or floors in several places. For this purpose porcelain tubes should be used, costing one to three cents each. Knock holes in the plaster at the determined 180 ELECTRICITY FOR THE FARM point, insert the tubes so they project % inch on each side, and fill up the ragged edge of the hole neatly with plaster. PORCBLAIH GUT-OUTS CO -MAINS TO ENTRANCE SWITCH DDD- BRANCH LAMP CIRCUITS IN WOODEN MOLDING- FFF ~ FU<5E PLUGS The distributing panel When all the tubes have been set in place, begin laying the moulding. Run it in a straight line, on the wall against the ceiling wherever possible, mitering the joints neatly. Whenever it is necessary to change the run from the ceiling to the wall and a miter cannot be made, the wires should be protected in WIRING THE HOUSE 181 passing from one slot to the other by being enclosed in non-metallic flexible conduit, called circular loom. In running wooden moulding, avoid brick walls liable to sweat or draw dampness; keep away from places where the heat of a stove might destroy the rubber insulation of the wires; do not pass nearer than six inches to water pipes when possible and when it is necessary to pass nearer than this, the wooden moulding should pass above the pipe, not below it, with at least an inch of air space intervening, thus avoiding dampness from sweating of pipes. WALL SWITCH Snap switch connections Places where chandeliers or wall bracket lamps are to be installed permanently are fitted with wooden terminal blocks, which fit 182 ELECTRICITY FOR THE FARM over the moulding and flush with the plaster. These, after holes have been bored in them for the wires, and the wires drawn through, should be screwed firmly to the wall or ceiling, always choosing a joist or beam for support. Then a crow's-foot, or tripod of iron, tapped and threaded for iron pipe, is screwed to the terminal block. The iron pipe of the chan- delier or wall bracket is then screwed home in this crow's-foot. Do not begin stringing wires until all the moulding of the circuit has been laid. Then thread the wires through the wall or floor .tubes and lay them in their respective slots. If trouble be found making them stay in place before the capping is put on, small tacks may be driven into the moulding beside them to hold them. When a terminal block is reached, a loop is made of each wire, through the hole cut in the block, if the circuit is to continue in the same direction. If it is to end there, the two wires are drawn through taut, and cut off at a length of 5 or 6 inches. These end wires, or loops, are then scraped bare and WIRING THE HOUSE 183 spliced to the two wires coming out of the chandelier or wall bracket. This joint is then PO&PQ&WBLEOZRD 3- BRANCH BLOCK CC~ CEILING D -FLOOR BOX EE~ PORCELAIN TUBES FFFF- WALL Detail of wooden moulding soldered and covered with tape, and the shell of the chandelier is screwed into place, covering the joint. 184 ELECTRICITY FOR THE FARM If the moulding is run along the walls flush with the ceiling, as is usual, a branch is made for a wall light, or wall tap, by means of a porcelain "T," or branch -block, which pro- vides the means for running the circuit at right angles to itself without letting the wires come in contact with each other where they cross. Separable current taps should be in- stalled in handy places on all circuits, so that small heating devices may be used without removing the lamps from their sockets. The two wires are bared for half an inch where they run through these current taps, and are fastened by means of brass screws. * ' Multiple ' ' Connections All electric devices for this installation lamps, irons, vacuum cleaners, motors must be connected across the circuit that is, bridged, from one wire to the other. This is called multiple, or shunt connection. There is only one exception to it, in wiring the house. That one exception is installing a wall switch, the ordinary snap switch. Since this w r all WIRING THE HOUSE 185 switch, is, in effect, merely an instrument, which opens or closes a circuit, it should be connected to only one wire, which is cut to provide two ends for the screw connections in the switch. When a moulding branch is run down from the ceiling to some convenient spot for a snap switch (with which to turn the lights of a room on or off), a porcelain "T" is not used. All that is necessary to do is to loop the bottom wire of the circuit down through the branch moulding, and connect it to the switch at a terminal block, or porcelain base. In wiring lamp fixtures, No. 14 rubber- covered wire will usually prove too large. For this purpose, No. 18 may be used, with one lamp to each loop. Hanging lamps may not be supported by electric lamp cord itself, if there is more than one lamp in the cluster, because the weight is apt to break the elec- trical connections. In such a case, the lamp should be supported by a chain, and the twisted cord conveying current to the electric bulbs, is woven in the links of the chain. For the pantry, kitchen, woodshed, barn, etc., a 186 ELECTRICITY FOR THE FARM single hanging lamp may be suspended from a fielding rosette, as shown in the cut, provided a single knot is tied inside both the rosette and the lamp socket, to make it secure. This ZxAJ^P .SOCKET TAKEZTJLPA&T Detail of simple hanging lamp supported by rosette makes a very cheap fixture. The rosette of porcelain will cost 15 cents; the lamp socket 20 cents, and the lamp cord suspending the lamp and carrying the current will cost 1J^ cents a foot; while a tin shade will cost another 15 cents. WIRING THE HOUSE 187 Official Inspection In all communities, your insurance agent must inspect and pass your wiring before you are permitted to throw the main switch and turn on the electricity. Frequently they re- quire that the moulding be left uncapped, until they have inspected it. If you have more than 660 watts in lamps to a circuit; if your joints are not soldered and well taped; if the moulding is used in any concealed or damp place, the agent is liable to condemn your work and refuse permission to turn on the electricity. However the rules are so clearly defined that it is difficult to go wrong; and a farmer who does his own wiring and takes pride in its appearance is more apt to be right than a professional electrician who is careless at his task. After the work has been passed, tack on the moulding capping, with brads, and paint the moulding to match the woodwork. Wooden moulding wiring is perfectly satis- factory if properly installed. It is forbidden 188 ELECTRICITY FOR THE FARM in many large cities, because of the liability of careless workmanship. It should never be installed in damp places, or out of sight. If the work is well done, the system leaves nothing to be desired; and it has the additional advantage of being cheap, and easily done by any farmer who can use carpenter tools. Farmers with moulding machinery can make their own moulding. The code prescribes it shall be of straight-grained wood; that the raceways for the wires shall be separated by a tongue of wood one-half inch wide; and that the backing shall be at least | inch thick. It must be covered, inside and out, with at least two coats of moisture-repellant paint. It can be had ready-made for about 2 cents a foot. Special Heating Circuits If one plans using electricity for heavy-duty stoves, such as ranges and radiators, it is necessary to install a separate heating circuit. This is the best procedure in any event, even when the devices are all small and suited to WIRING THE HOUSE 189 lamp circuits. The wire used can be deter- mined by referring to the table for carrying capacity, under the column headed "rubber- covered." A stove or range drawing 40 amperes, would require a No. 4 wire, in moulding. A good plan is to run the heating circuit through the basement, attaching it to the rafters by means of porcelain knobs. Branches can then be run up through the floor to places where outlets are desired. Such a branch circuit should carry fuses suitable to the allowed carrying capacity of the wire. Knob and Cleat Wiring Knob and cleat wiring, such as is used extensively for barns and out-buildings, re- quires little explanation. The wires should not be closer than 2^ inches in open places, and a wider space is better. The wires should be drawn taut, and supported by cleats or knobs at least every four feet. In case of branch circuits, one wire must be protected from the other it passes by means of a porce- lain tube. It should never be used in damp 190 ELECTRICITY FOR THE FARM places, and should be kept clear of dust and litter, and protected from abrasion. Knob and tube wiring is frequently used in houses, being concealed between walls or ^