*!**" 
 
 THE 
 
 THERMOMETE 
 
 .AND ITS 
 
 FAMILY 
 TRE E 
 
 K> 
 
THE 
 
 ITS 
 
 K/VMILJV 
 TREE 
 
 fy 
 
 PUBLISHED BY 
 
 TAYLOR INSTRUMENT COMPANIES 
 MANUFACTURERS OF METEOROLOGICAL INSTRUMENTS 
 ROCHESTER, N.Y. U. S. A. 
 
"V o 
 
 Copyright 1914 
 
 by 
 
 Taylor Instrument Companies 
 Rochester, N. Y. 
 
THE: R,:MOMETER, 
 
 IN looking at a thermometer apparently a glass tube contain- 
 ing either quicksilver or a coloured liquid and placed upon a 
 divided and figured plate of some description one is not apt 
 to realize the thought, skill and research it has taken to bring this 
 simple, yet universally necessary article to its present status. 
 
 For many centuries scientists have worked 
 in an endeavor to perfect it, but only during 
 the past forty years have they found out all 
 the details necessary to the manufacture of a 
 more or less perfect article. 
 
 Many people are credited with its inven- 
 tion, Drebbel, a Hollander, being referred to 
 more than any other, but to Galileo Galilei the 
 laurels should be handed. 
 
 According to history it seems that about 1592 
 he invented at Padua an instrument described 
 as "a glass containing air and water, to indi- 
 cate changes and differences in temperature." 
 
 With the idea started, 
 the Grand Duke of Tus- 
 cany investigated this 
 "invention," and more or 
 less perfected it between 
 1630 and 1640. 
 
 The original thermometer consisted of a 
 glass tube about 16 inches in length with a 
 hollow ball or bulb fitted at the end. The 
 whole was heated until the air inside be- 
 came rarified, when the open end was placed 
 in water, the tube being kept upright. 
 
 As the air in the tube cooled or con- 
 tracted, the fluid (water was originally 
 used) in the tube rose to a certain point and 
 
 anv subsequent changes caused the level of 
 
 .1 * n .-i . ., THE SAXCTORIUS 
 
 the fluid in the tube to be either elevated or THERMOMETER 
 
 depressed. ABOUT 1620 
 
 THE DREBBEI. 
 
 THERMOMETER 
 
 ABOUT 1592 
 
 3O2RRQ 
 
This was used by Sanctorius as a "heat measure" or fever 
 thermometer. It is on record that he had his patients hold the 
 top of the "thermometer" so the level of the fluid would be 
 arrested at a point equal to the temperature of the person hold- 
 ing it. A "point" was undoubtedly determined by a normal, 
 healthy person beforehand and it is reasonable to assume that 
 Sanctorius drew his deductions by noting the distance above or 
 below this "normally healthy" point. 
 
 M. Jean Roy,, a French physician of note, made a thermometer 
 similar to the one originally designed by Drebbel, but filled it 
 with alcohol instead of water. He did not invert his "thermom- 
 eter" but kept it in an upright position and noted the rise and 
 fall of the spirit due to the expansion or contraction of it. This 
 was about 1630. 
 
 Before ten years had passed, the Grand Duke of Tuscany 
 had carried out his idea of first partly filling the tube with 
 alcohol and closing the open end, thus sealing it and excluding 
 the air. 
 
 Realizing that the level of the liquids in these various instru- 
 ments meant nothing, pupils of Galileo sought to make a scale 
 of temperature and melted on to the tube of their thermometers 
 small glass balls about the size of a pin's head, the zero of the 
 "scale" being the point to which the liquid fell in a freezing 
 mixture of salt and water. 
 
 For the next hundred years or so the deepest confusion 
 occurred, for not only had various types of instruments been 
 invented, but no two of them agreed as regards their graduation. 
 Many schemes and devices were used to determine satisfactory 
 scales, but agreement could not be easily made. 
 
 In a book written in 1738 by Bernandinus Teleius great 
 attention is given to this matter. 
 
 At one time, it seems the bright minds of Europe decided that 
 the freezing point of liquors varied to such an extent that it 
 could not be used as a test point, and suggested taking the 
 temperature 
 
 "In a carte cut straight into the bottom of a cliff front- 
 ing the sea to the depth of 130 feet, with 80 feet of earth 
 above it." 
 Speaking of this, the author says: 
 
 "But with Dr. Hole's leave, this degree of tempera- 
 ture I do not think a very convenient term for universal 
 construction of thermometers. Everybody cannot go to 
 Mr. Boyle's grotto; and it is but few who can have an 
 opportunity of making observations and adjusting ther- 
 mometers in the cave of the 'Parisian Observatory.' '' 
 
 4, 
 
In speaking of the scale laid out by Sir Isaac Newton as 
 having test points at freezing water, the heat of the human body,, 
 boiling water and melting tin, he says: 
 
 "I wish the world would have received this or any 
 
 other determined scale for adjusting their thermometers, 
 
 but I suppose they might be apprehensive of some incon- 
 venience in this scheme." 
 
 Robert Hooke and Hon. Robert Boyle,, of the "Royal Society 
 in London/' were the first to realize the necessity of having a 
 standard scale. About 1662, Hooke, placing his instrument in 
 freezing distilled water, marked "zero" at the top of the column 
 of spirit after immersion of the bulb. Soon after, he suggested 
 that the second point should be the boiling point of water; but 
 this does not seem to have been adopted at that time. 
 
 Delance suggested that the freezing point of water should 
 be marked "cold" (-10), the melting point of butter "hot" 
 (-(-10), and the space midway between "temperate" (0), with 
 ten divisions between each. 
 
 In 1714, Fahrenheit of Dantzig designed a scale for ther- 
 mometers which showed the freezing of water at 32 and the 
 boiling of water at 212. 
 
 Many suggestions have been made as to why he graduated 
 the freezing and boiling of w r ater into 180 divisions, one being 
 that as he was an astronomical instrument maker, and as his 
 machines divided to full circles (360 divisions), he used a half 
 circle for his scale. 
 
 Seventeen years later, Reaumur, a French physicist, designed 
 a scale on which the freezing point of water appeared as 
 degrees, the scale between this and the boiling of water being 
 divided into eighty equal parts. 
 
 Anders Celsius, Professor of Astronomv at the University of 
 Upsala, proposed a scale in 1742, and called the freezing point 
 of water 100 and the boiling point of water 0. These points 
 were afterwards reversed by Christin of Lyons (France) in 
 1743, and the result is the well known Centigrade scale. 
 
 Athanasius Kircher was the first to use quicksilver in ther- 
 mometers, although Delance once remarked "curious people use 
 it," little dreaming that one day it would become universal in 
 use. 
 
 In speaking of the faults of different liquids used in the early 
 manufacture of these instruments Teleius remarks: 
 
 "We have, it seems, nothing left but quicksilver. 
 "This is a very movable, and ticklish fluid; it both 
 
 heats and cools faster than any liquor we know of or have 
 
 had occasion to try." 
 
 5 
 
Quicksilver and alcohol have been accepted by the scientific 
 world as a convenient and accurate means to indicate the tem- 
 perature of anything with which the tube containing them may 
 come in contact. 
 
 For high temperatures quicksilver is used, for it 
 
 FREEZES AT -38 Fahrenheit, -38 Centigrade 
 AND BOILS AT 674.6 Fahrenheit, -357 Centigrade 
 As the freezing point of mercury is fairly high,, alcohol ther- 
 mometers are invariably used in very cold climates,, for this 
 liquid 
 
 FREEZES AT -202.9 Fahrenheit, -130.5 Centigrade 
 AND BOILS AT 173.5 Fahrenheit, 78.5 Centigrade 
 From this it will be seen that quicksilver is unsuitable for any 
 very low temperature and alcohol is unsuitable for any very high 
 temperature. 
 
 THE CONVERSION OF THERMOMETER SCALES 
 
 Centigrade to Fahrenheit 
 
 To convert Centigrade degrees to degrees of Fahrenheit, 
 multiply by 9, divide the product by 5 and add 32. When the 
 temperature Centigrade is below Cent, deduct 32 instead of 
 adding. 
 
 Fahrenheit to Centigrade 
 
 To convert Fahrenheit degrees to degrees of Centigrade, sub- 
 tract 32, multiply by 5 and divide by 9. When the temperature 
 Fahrenheit is below Faht. add 32 instead of subtracting. 
 
 Reaumur to Fahrenheit 
 
 To convert Reaumur degrees to degrees of Fahrenheit, multi- 
 ply by 9, divide by 4 and add 32. When the temperature 
 Reaumur is below Reau. deduct 32 instead of adding. 
 
 Reaumur to Centigrade 
 
 To convert Reaumur degrees to degrees of Centigrade, multi- 
 ply by 5 and divide by 4. 
 
 Centigrade to Reaumur 
 
 To convert Centigrade degrees to degrees of Reaumur, multi- 
 ply by 4 and divide by 5. 
 
 C Water Freezes at 77* Water Freezes at 32 
 
 ent. " Boils " 100 JT aht. " Boils " 212 
 
 Water Freezes at 
 .eaumur " Boils " 80 
 
 R 
 
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 170 
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 ce 
 
 THE THREE STANDARD SCALES FOR THERMOMETERS 
 
THE MAKING OF 
 GLASS THERMOMETER TUBING 
 
 As the value of a thermometer depends to a great extent on 
 the grade of glass and the care taken in making and drawing it 
 into the tubes, a few words regarding it will be of help to the 
 reader and will give an idea of how the small "hole" or "bore" 
 up which the quicksilver travels, is formed in the glass. 
 
 Glass is hard, brittle and transparent. It is formed by fus- 
 ing together mixtures of silicates of potash, soda, lime, magnesia, 
 alumina and lead in various proportions, according to the quality 
 or kind of glass required. 
 
 The first step in the manufacture of glass tubing is to take an 
 
 iron pipe, about five 
 feet long and collect 
 on about two inches of 
 the end of it (by 
 dipping it in molten 
 glass) a quantity of 
 glass about as large 
 as a quart milk jug. 
 When this glass is 
 still in a plastic state 
 (i. e., not hard) a 
 bubble is formed in 
 the centre of it by 
 blowing hard into the 
 end of the iron pipe. 
 The glass is then 
 rolled over a plate so 
 it becomes cylindrical 
 in shape (like the 
 tubular record of a 
 phonograph) but 
 solid, except for the 
 hole in the centre 
 caused by blowing 
 through the iron pipe. 
 
 This rolling process causes the roughly blown round hole in the 
 glass to attain a cylindrical shape more or less perfect in 
 appearance. 
 
 The next process is to flatten the glass, which is accomplished 
 by applying pressure to the top and bottom of the mass. This 
 operation causes the cylindrical hole in the centre to flatten out 
 a trifle, due to pressure, and to appear in the shape of a thick 
 ribbon instead of a circular hole. 
 
 8 
 
 ROLLING THE GLASS MASS 
 
White enamel glass is then put on that part of the tube which 
 is directly behind the "hole" or, as it is called in the finished 
 thermometer, the "bore." 
 
 The mass is now put into hot glass so it is absolutely covered 
 with a new coat of it. During all these processes the glass 
 develops "waviness" and to get it into proper condition and 
 solidity it has to be rolled on iron slabs. The outside is chilled 
 somewhat, so the inside retains its correct shape. 
 
 In order to properly read the quicksilver in the column, a 
 great many tubes have "lens" fronts. This lens is formed on the 
 glass by putting it in a "V" shaped mould with the white enamel 
 glass uppermost. The mass then represents a wedge with a 
 rounded top. 
 
 Now remember what has been done to this glass to make 
 tubing from it. A hole has been blown in the centre of the 
 original "lump" of glass ; it has been rolled out, flattened on the 
 
 top and on the bottom, it has had 
 white enamel put upon the back, and 
 has been covered with a second coat- 
 ing of glass. Finally it has been 
 rolled again to take imperfections 
 out and then the lens has been 
 formed on the front. 
 
 At this point it looks like a piece 
 of glass tubing about 5 inches thick 
 and 9 inches long, on the end of an 
 iron tube with a long bubble in the 
 centre, some white glass behind the 
 bubble and the glass formed in 
 a "V" or wedge in front of the 
 bubble. 
 
 Now the delicate operation comes 
 of "pulling this glass out" or 
 "stretching" it into the small thin 
 canes of tubing such as are used in 
 thermometer making. 
 
 The mass of glass is put on a hot 
 iron plate six or eight inches in 
 diameter, with the iron tube through 
 which the hole was blown pointing 
 upwards. This tube is secured to a 
 
 wire cable extending upwards for about 150 feet, which is 
 
 attached to a motor. 
 
 The glass is now ready and the motor is put in operation, 
 
 9 
 
 DRAWIXG PLASTIC GLASS 
 IXTO TUBES 
 
with the result that the plastic glass is pulled upwards for about 
 150 feet into a more or less perfect tube. 
 
 The hole which was originally blown in the centre becomes 
 the minute hole up and down which the quicksilver travels ; the 
 white enamel glass becomes the white back of the thermometer 
 tube, and the "V" front becomes the magnifying lens. 
 
 The tubing is now ready for cutting up into "canes," or 
 lengths of glass, to be used for tube making. The ends of the 
 length after drawing are useless, due to distortion in forming them. 
 
 Great care has to be taken in sorting this glass, for the size 
 of the hole or "bore" in the centre of the glass varies, and as 
 a consequence quicksilver or spirit will rise slowly up a tube hav- 
 ing a large bore, and quickly up a tube having a small bore, if the 
 bulb or quicksilver ends of the thermometer are of the same size. 
 
 A 
 
 | 
 
 B 
 
 A THERMOMETER BORE 
 B HUMAX HAIR 
 
 In some thermometers the "bore" is very much finer than the 
 diameter of a human hair, and the relation of the capacity of the 
 bulb which holds the quicksilver to the tube up and down which 
 it travels, is roughly 1000 to 1. 
 
 The "grading" of these tubes calls for the work of an expert, 
 for it can only be done by putting the end of the glass to a 
 powerful microscope and measuring the "bore" by means of hair 
 lines under magnification. 
 
 This practically completes the making of glass tubing. 
 
 THE MAKING OF THE THERMOMETER TUBE 
 
 The lengths of glass tube, or "canes" as they are called, are 
 now cut into pieces twice the size of the thermometer into which 
 they will ultimately be turned. 
 
 The sharp flame of a blow pipe is made to play in the centre 
 of the tube. When it has become warm enough it can be pulled 
 apart, making two complete tubes, each of the same size and each 
 sealed at one end. 
 
 10 
 
MEASURING THE BOBE OF A TUBE 
 
 One of these tubes is now taken and an ordinary rubber bulb 
 is fitted to the OPEN end. 
 
 The CLOSED end is now heated., pressed and manipulated until 
 the glass is more or less solid at this end. If the rubber bulb is 
 now pressed, air is forced down the tube and when it reaches 
 the molten end a bubble is formed. This bubble is called the 
 bulb. (See illustration page 13). 
 
 In the manufacture of thermometers of anything above good 
 grade, special hard glass is melted on to the end of the tube, so 
 that the bulb is formed from this glass instead of from the tube 
 glass. 
 
 Sometimes these bubbles or bulbs are made large and some- 
 times small it all depends on what is required of the finished 
 thermometer. If the bore in the tube is large and the bulb 
 large, or if the bore in the tube is small and the bulb is small, the 
 quicksilver will rise much more slowly in the tube than if the bore 
 is small and the bulb large. 
 
 Every tube, therefore, having a certain bore must have a cer- 
 tain sized bulb to make it work in a particular manner. If it 
 were required to create a thermometer in the Fahrenheit scale 
 with the "freezing" at a certain point say \ ff from the bulb, 
 and a 120 point, say J" from the top of the tube, the bore of the 
 tube would have to be measured and the bulb would have to be of 
 a certain exact size. 
 
 It is possible with a microscope to measure the bore 
 accurately and it is possible to determine the size the bulb should 
 
 11 
 
FILLIXG A TUBE WITH QUICKSILVER 
 
 be, but it is impossible to make it work so that at certain tempera- 
 tures the quicksilver would stand at a number of predetermined 
 points on the tube. 
 
 Plates having different sized holes in them are supplied to 
 the tubemakers and with the workman's knowledge of the size of 
 the bore, the approximate size of the bulb can be determined 
 when they know the lowest point and the highest point the 
 thermometer will be required to register. For instance, a bulb 
 \" in diameter might, if fitted to a tube having a certain bore, 
 have a range of scale showing 200 from its highest point to its 
 lowest point. If the bulb was made \" in diameter, the range 
 of scale might be equal to 50. 
 
 After the bulb has been formed to the correct size, and while 
 it is still hot, the open end of the tube is placed in a jar of pure, 
 clean quicksilver. As the glass cools, the air in the bulb and 
 tube contracts, drawing the quicksilver up into it. 
 
 This process will only partially fill the tube and in order to 
 complete it, the tube after cooling is taken out of the jar, and 
 with the bulb downwards more heat is applied, when it is 
 again inverted in the jar and so on, until the bulb and tube are 
 completely filled. 
 
 A process known as "roasting" is carried on, to expel every 
 particle of moisture. 
 
 In order to properly seal and close the tube, a gas flame is 
 blown across the top of it until the glass becomes very plastic. 
 
 12 
 
BLOWIXG AXD GAUGING THE BULB 
 
 The top of the tube is now drawn away in exactly the same way 
 as it is drawn in the original manufacture very thin but still 
 having a very minute hole or bore in the centre. 
 
 Heating the bulb again drives the quicksilver to the top of the 
 tube once more and it travels along the newly made thin tube, 
 expelling all the air. If the glass at the extreme top of the main 
 tube, or at that portion of it which starts to thin out by the last 
 operation,, be melted, it will seal this hole and, providing the 
 operation is accomplished carefully, will prevent any air from 
 entering the thermometer, and the quicksilver will flow back to 
 the bulb of the tube as it cools. 
 
 This end, or hook as it is called, is used to securely fasten the 
 thermometer tube to its scale. 
 
 The thermometer tube is now complete, for a bulb has been 
 formed at the end, the tube and bulb have been filled with quick- 
 silver, the air expelled and the end sealed. The quicksilver is 
 now free to move up and down the tube as soon as temperature 
 changes either expand or contract it. When the surrounding air 
 gets warmer the quicksilver expands and rises in the tube and 
 when the surrounding air gets cooler it contracts and falls. 
 
 Although we have our tube, bulb and quicksilver made satis- 
 factorily, we have not a thermometer, because the height of the 
 quicksilver in the tube for any temperature has not yet been 
 determined. 
 
 To properly accomplish this it is necessary to have water in 
 receptacles of different temperatures, one at 32 Faht., one at 
 62 Faht., and another at 92 Faht , if the thermometer is to be 
 used for ordinary living or room temperature. 
 
 13 
 
The 32 Faht. point is obtained by crushing ice, as 32 Faht. 
 is the temperature of either freezing water or melting ice. A 
 point 2 Faht. is obtained on some thermometers, being reached 
 by a brine solution. 
 
 In each of these "baths" a thermometer of known accuracy is 
 placed and left immersed a sufficient time to enable the quick- 
 silver to come to rest, thus determining the correct temperature 
 of the water, which must be constantly agitated, in order to keep 
 it from becoming cooler on the sides than in the centre, or vice 
 versa. 
 
 Water in thermometer manufacturing is mechanically con- 
 trolled at the necessary temperatures, but if by chance it should 
 rise or fall below the desired point, it can be readily adjusted by 
 introducing either cold water or steam, dependent on the condi- 
 tion of it. 
 
 If the bath is controlled and has a temperature of 62 Faht., 
 the thermometer tube which has to be tested is put in and, when 
 the quicksilver has come to rest, a line is put upon the tube at the 
 level of the quicksilver, thus indicating the point at which the 
 quicksilver stands when the temperature is at 62 Faht. This 
 operation is repeated in a bath of 92 Faht., and also in crushed 
 ice at 32 Faht. A point 2 above zero Fahrenheit is reached in 
 cold brine. 
 
 Four marks, divisions, or "points" as they are called, have now 
 been determined and if they are equidistant it is reasonable to 
 assume that each can be sub-divided into thirty equal divisions, 
 i. e., from 2 to 32, from 32 to 62, and from 62 to 92. The divi- 
 sions can be extended below 2 and above 92 at the same ratio with 
 reasonable accuracy. 
 
 A brass plate is now taken, which when completed will form 
 the scale or face of the thermometer, for upon it the graduations 
 have to be placed, also the figures. 
 
 The thermometer -tube is set upon this plate and the marks 
 which denote 2, 32, 62, and 92 Faht., are reproduced in 
 exactly the same positions upon it. A dividing machine is 
 arranged to cut or engrave the necessary divisions. It can be 
 finished in any desired style and the thermometer tube perma- 
 nently placed upon it. Great care must be exercised in seeing 
 that the points on the tube agree exactly with the same points on 
 the scale. 
 
 This practically completes a common tvpe of thermometer. 
 Refinements in manufacture are many and there are various and 
 obvious reasons why a thermometer apparently looking the same 
 as another should cost two, three or even four times as much. 
 
 14 
 
ERRORS WHICH MUST BE GUARDED AGAINST 
 
 MANUFACTURING 
 
 (A) Careless "pointing" of the tube will, of course, result in 
 erroneous readings and it is one of the most common sources of 
 trouble in practical thermometrv. 
 
 This can be caused through inefficient labour, through care- 
 lessness in placing the points upon the tube,, or in letting the test 
 baths get either too cool or too warm, during the pointing process. 
 
 Occasionally the thermometer tube will slide from its position 
 on the scale and naturally all indications will be reading either 
 above or below the true reading. 
 
 (B) If the bore of the tube is erratic, the quicksilver will 
 naturally rise more slowly in parts which are larger, and faster in 
 parts which are smaller. 
 
 The theory of this was pointed out on page 11, which ex- 
 plained the connection between the bulb and the bore. The 
 smaller the bore the quicker the rise of the quicksilver in the tube. 
 
 (C) Impurities in the quicksilver make the bore of the tube 
 rough and if the quicksilver is dusty, particles of it will stick to 
 the bore of the tube, and besides being unsightly it will cause the 
 quicksilver to appear sluggish in its action. 
 
 (D) As glass shrinks after manufacture, it is necessary in 
 order to have a thermometer keep its readings correct, to make 
 sure the glass is properly "seasoned." 
 
 The shrinkage of glass is imperceptible, but it is easy to 
 realize that if the bulb and bore of the tube contract the smallest 
 amount, the quicksilver will be driven higher in the tube, so that 
 a point, say 40 Faht., might be correct on the scale made for the 
 tube when new, but after the tube had contracted, or shrunk, or 
 become seasoned, might read 46 Faht., or even 48 Faht., 
 depending on the quality of the glass. The only way to over- 
 come this is to keep tubes in storage for eighteen or even twenty- 
 four months before determining the "points," so that all contrac- 
 tion of the glass will have passed and the indications will be 
 permanently accurate. 
 
 15 
 
BLUNDERS WHICH CAN BE AVOIDED 
 
 OBSERVING 
 
 (A) Nothing is so disheartening to an observer of tempera- 
 ture, whether he be noting temperature of a room, the soil, the 
 outside air, or whatnot, as readings which he feels he cannot 
 rely on. 
 
 Naturally it is essential in the first place that the thermometer 
 being used is of known accuracy and will remain so. A little 
 extra cost in the original purchase of a thermometer will never 
 be regretted. 
 
 (B) All thermometers are affected by the surrounding air. 
 When observing the readings be careful not to stand so near the 
 bulb that it will be affected by the warmth of your body or 
 breath. This is a continual source of trouble, especially if the 
 thermometer.be a very sensitive one. 
 
 (C) Take great care in noting the proper division on the 
 scale. Some thermometers have their divisions in 2 lines, some 
 in 1 lines, some in ^ lines and some in 1-5, 1-10, etc. Errors 
 are often made in reading 2 lines as 1 lines. 
 
 (D) In reading be sure and get the eye level with the quick- 
 silver. If you read it from below the reading will appear too 
 high, and if from above too low. 
 
 (E) In moving a thermometer into a fresh place remember 
 it takes some time for it to adjust itself to the new temperature. 
 This, of course, depends on the sensitiveness of the instrument. 
 Fanning it, or passing it carefully through the air for some 
 time will greatly help it. 
 
 (F) Beware of the word "Standard !" It is a most abused 
 term ! The word is placed on some thermometers that are not 
 standard in any sense of the word. In experience the writer has 
 found thermometers marked this way with errors varying from 
 3 to 10 Faht. 
 
 (G) Do not condemn a thermometer because it does not 
 agree with one hung near it. Remember these instruments indi- 
 cate the temperature of the air which surrounds THEM and NOT 
 the temperature of the air one inch or twelve inches away. 
 
 16 
 
TYPES OF THERMOMETERS 
 
 The style of thermometer ordinarily used for the purpose of 
 
 determining the temperature of rooms, offices, corridors, etc., is 
 
 that having a metal plate with the thermometer tube set upon it, 
 
 the whole being fitted to a wooden back, of varied 
 
 styles and descriptions. 
 
 Such a thermometer is very satisfactory, pro- 
 viding it is not influenced by direct sunshine, 
 draughts, open windows, radiators, air furnaces, 
 etc. Care should be taken when fitting it on the 
 wall to see that no chimneys or air shafts pass 
 through that part of the wall, causing it to be exces- 
 sively hot or cold. When convenient a thermometer 
 should be set two or three inches away from a wall, 
 so that it may get correct circulation of air around it. 
 The most satisfactory height for a room ther- 
 mometer is about 60 inches to 70 inches above the 
 floor. Thermometers having coloured alcohol in them 
 in place of quicksilver can be much more quickly 
 read, but they are somewhat sluggish in their work- 
 ing, compared to those in which quicksilver is used. 
 Sometimes the alcohol may become separated 
 from the main column, but it can be easily joined to 
 ROOM ** ky swinging the thermometer sharply backwards 
 
 THER- and forwards with a pendulous motion, taking care 
 MOMETER that the bulb is downwards. It is also desirable to 
 occasionally examine the upper part of the tube and 
 to see that it is perfectly free from detached portions of alcohol. 
 An easy method of correcting this is to take the thermometer with 
 the bulb in the right hand and strike the top against the palm of 
 the left hand. The alcohol at the top of the tube will slowly 
 start to run down towards the main column. When detached 
 portions are joined, the thermometer should be allowed to stand 
 in an upright position for about half an hour. 
 
 This simple form of thermometer gives indications of existing 
 temperatures. In sick rooms, greenhouses and many other 
 places, it is interesting and sometimes necessary to have a knowl- 
 edge of what the temperature has been. For this purpose a ther- 
 mometer capable of giving maximum and minimum temperatures 
 is used. The one most common, interesting, and effective is a 
 pattern designed by Mr. James Sixe, of Canterbury, England. 
 It consists of a glass "U" shaped tube with the ends terminating 
 sometimes in round balls and sometimes in a ball at one end and 
 a glass cylinder at the other. The latter pattern is in all ways 
 
 17 
 
preferable. The tube is completely filled with creosote to within 
 almost one-half inch of its top, which is filled with air. Prior to 
 this quicksilver has been put into the lower portion of the "U," 
 but NOT for the working member, as popularly supposed. 
 
 If the illustration be examined it will be found that the left 
 side scale is figured from 120 at the bot- 
 tom to 40 at the top, while the right hand 
 side is practically the reverse of this. 
 
 The creosote in the tube in the centre 
 expands when the temperature increases, 
 driving the quicksilver down on the left 
 hand side and up on the right hand side, 
 thus increasing the air pressure in the right 
 hand bulb. As th.e right hand side shows 
 an increase in its scale reading it is called 
 the "Heat or Maximum" side of the tube. 
 
 If the temperature lessens, the creosote 
 will contract so that the quicksilver 
 will fall on the "Heat" side and rise 
 on the "Cold" or "Minimum" side, 
 which shows the thermometer scale 
 decreasing. 
 
 Indices are carefully made and 
 inserted in the tubes above the levels of the 
 quicksilver, so they can be used to indicate 
 the highest and lowest point the thermometer 
 has reached since its last setting. 
 
 The index is a miniature glass bottle with 
 a small piece of steel wire inside it. Steel is 
 used so that the index can be raised or 
 lowered by means of a magnet, which can be 
 moved up and down in front of the tube. In 
 order to keep the index from receding with 
 the quicksilver, two hair-like appendages are 
 fitted to it (one of these is fastened to the 
 bottom and points upwards, the other is 
 fastened to the top and points downwards). 
 HIGH AXD Low ^ s ^ e quicksilver rises on either the "Heat" 
 THERMOMETER or "Cold" side, the index is raised on the sur- 
 
 "SIXE'S TYPE" face of it, and when the quicksilver recedes 
 
 the index remains stationary until reset with 
 
 a magnet. It will then indicate the highest and lowest reading 
 since its last setting. Another type of thermometer to give 
 maximum and minimum temperatures is shown on page 19. 
 
 18 
 
HIGH AXD Low THERMOMETERS. HORIZONTAL TYPE 
 
 This consists of two separate thermometers set horizontally, 
 one to give maximum readings and the other minimum. The 
 maximum instrument is quicksilver-filled, the tube being arranged 
 in such a manner that when the temperature cools the quicksilver 
 cannot, by itself, set back into the bulb. This allows it to remain 
 indefinitely in the tube. In order to reset it, it is necessary to 
 swing it sharply a couple of times, when the quicksilver will 
 easily and quickly be driven back into its bulb. 
 
 The minimum thermometer is alcohol-filled and has a small 
 index set in the fluid. By holding the thermometer upside down 
 this index \vill flow down the alcohol to the end. It should now 
 be placed horizontally. When the air cools the alcohol is natur- 
 ally drawn toward the bulb, bringing the index with it. When it 
 rises again the index is left stationary in the tube, indicating the 
 lowest, or minimum, temperature. To reset it, invert the ther- 
 mometer, when the index will flow again to the end of the alcohol 
 column. 
 
 As they are of approved standard type, the thermometer 
 tubes have the temperature divisions etched upon them. This is 
 duplicated every 5 or 10 on the scale itself. 
 
 Any thermometer marked "Standard" and not having its scale 
 divided and etched directly on the tube itself, is not a standard 
 thermometer. Standard thermometers are always accompanied 
 with a certificate of correction which shows the error (if any), 
 so that true readings of temperature can be arrived at. 
 
 Thermometers with glass scales are made for exposure out- 
 side of windows, so that outside temperatures can be read from 
 inside. 
 
 The figures on the scale are either etched permanently upon 
 the glass or are painted upon it and baked in, so that water, snow, 
 sunshine, etc,, will neither fade nor wash them out. 
 
 Such thermometers are usually fitted outside the window, the 
 metal arms allowing them to be held far enough away to prevent 
 the warmth (in winter) from the window affecting them. 
 
 19 
 
A northern exposure is the best if it can be found, for the sun 
 will not then upset the readings of the instrument, as will be the 
 case if it be exposed on the south, where the sun will, when out, 
 always shine upon it. 
 
 In some instances it is necessary to have knowledge of what 
 the temperature has been during any previous period, or for any 
 particular time. An instrument known as a "thermograph" or 
 recording thermometer, is used for this purpose. 
 
 Instead of using a quicksilver or alcohol thermometer the 
 working part consists of a spiral metallic coil, which is very sen- 
 sitive to changes of temperature. To this coil is fitted an arm, 
 about seven inches long, to the end of which is fitted a pen which 
 
 RECORDING THERMOMETER 
 
 registers on a drum (containing a clock) the different changes as 
 they take place. 
 
 The clock rotates upon its axis once a week and has wrapped 
 round it a chart on which are divided the days of the week, each 
 day being divided into two-hour spaces. 
 
 20 
 
^ -Z&ttt 13 li 
 
 frrshiri :-'?; ', ? 7-' - r -- r - ~ > ? 
 
 1 ; n ! - liTiiW 
 * 
 
 CHART OF RECORDING THERMO3IETER 
 
 The pen on the arm rises and falls as the temperature in- 
 creases or decreases and as the clock revolves a tracing is made 
 on the chart, which also indicates the time at which such changes 
 occur. 
 
 In a greenhouse., sick room, or anywhere where temperature 
 is of consequence, the information one gains by consulting the 
 ordinary thermometer is not sufficient, for in the case of the green- 
 house, the thermometer early in the morning may show 4-5 
 Faht., but who is to know the extent of its fluctuations throughout 
 the night or if it went to or below the freezing point, killing all 
 the young growth which was being so carefully guarded? 
 
 The same applies to the sick room. It can be easily seen if 
 the temperature of the room is being maintained, or if it is 
 fluctuating materially. 
 
 Records can be filed and kept for reference, for one never 
 knows when such information may be needed. 
 
 There is one type of thermometer which can be found in the 
 most remote parts of the earth in the frozen Arctic and in the 
 sweltering tropics, men never travel without it. It is used 
 among the uncivilized as well as the civilized, by all races of 
 mankind, irrespective of colour or religion. It is called the 
 "fever" thermometer. 
 
 It is a well known fact that during health the same degree of 
 temperature is virtually maintained. No matter whether it be 
 winter or summer our bodies contain the same amount of heat if 
 they be in a normal, healthy condition. 
 
 They not only contain it, but do so with a beautiful and 
 natural exactness. 
 
 The temperature of a human being is not the same in all parts 
 of the body, so, to establish a common standard, the medical 
 fraternity accepted the temperature as taken under the tongue. 
 
 21 
 
In some cases (such as in young children and those suf- 
 fering from delirium),, this is not a practicable place,, so the 
 rectum, or a point under the arm is selected, although the 
 latter is not a very satisfactory point of contact, on ac- 
 count of the time the instrument takes to register the maxi- 
 mum temperature. 
 
 From a vast number of observations, a point 98.6 on 
 the Fahrenheit scale has been determined 
 as "Normal health." If the thermometer 
 should rise or fall, or fluctuate from this 
 point, the delicate mechanism of the body 
 is in some way deranged. Some people 
 are "subnormal" and others are "abnor- 
 mal," meaning that their individual and 
 correct temperature is a fraction of a de- 
 gree below or above the 98.6 Fahrenheit. 
 
 The 
 
 average, as are 
 
 all 
 from 
 
 averages, 
 good 
 
 was probably determined 
 many thousand readings. 
 
 Fever thermometers are made to regis- 
 ter the maximum temperature by leaving 
 the quicksilver end under the tongue for 2 
 minutes, 1 minute, or ^ minute. The tube 
 is made in such a manner that while the 
 quicksilver will rise in the tube as the 
 temperature increases, it will not "set 
 back" to the bulb after it is taken from the 
 mouth and becomes exposed to a lower 
 temperature. This is called a "self-regis- 
 tering" feature and it is necessary after each 
 observation to hold the thermometer firmly by 
 the upper end with the bulb downward and 
 swing or shake it in such a manner as to force 
 the quicksilver back toward the bulb. 
 
 The instrument should be carefully cleansed 
 after each reading, to prevent the spread of any 
 infection, and should be kept in as sanitary a 
 case as possible. 
 
 Since a fever thermometer must be and must 
 remain of absolute standard accuracy, it is easy 
 to see that good ones cannot be cheap in price 
 and that they cannot be purchased for a "mere 
 trifle." 
 
 If the glass is not properly "seasoned," if 
 the "points" are not most carefully determined 
 
 Industrial type 
 o f thermometer 
 to 750 Faht. for 
 determining tem- 
 perature of super- 
 heated steam. 
 
and if the scale is not accurately /hYMedy thkrmsiJumenc is more 
 than useless. 
 
 An accurate fever thermometer is of untold value in a house, 
 hospital, travelling kit, or whatnot, but an inaccurate one is a 
 positive danger to the owner. 
 
 Thermometers for specific purposes have to be manufactured 
 in a certain manner, both as regards their style and adjustment. 
 A thermometer is always a thermometer, but it is impossible to 
 make a single thermometer to cover a multitude of purposes. 
 For instance, a thermometer used to indicate room temperatures 
 is quite impracticable as a thermometer for indicating the tem- 
 perature of the various mixtures used in candy making. 
 
 Thermometers are used in the manufacture of asphalt, candy, 
 coal, oil, wood drying, tobacco, milk, artificial teeth, dough, ham, 
 ice cream, maple and ordinary sugar, and are used in connection 
 with babies' food, the bath, brewing, incubating, cold storage, 
 fruit evaporating, hop curing, milk testing, photography, the soil, 
 hot water heating, milk pasteurizing and sterilizing, orchards, 
 railway coaches, refrigeration, veterinary work, vulcanizing, and 
 a thousand and one other purposes, each one being of special 
 design and especially adapted for its individual use. 
 
FOR THE AMATEUR 
 
 By P. R. Jameson, F. R. Met. Soc. 
 
 "Practical Hints for Amateur Weather Forecasters." Twenty pages 
 illustrated of information on the care and exposure of barometers, 
 how to set for sea level, effect of temperature on the weather, etc., 
 Beaufort's scale of winds, general indications and approximate 
 forecast for the whole of the barometer scale, for either rising or 
 falling indications. 
 
 10 cents postpaid, stamps or silver 
 
 "Humidity, Its Effect on our Health and Comfort." Twenty-four pages, 
 illustrated on matters concerning the necessity of correcting present 
 day inside moisture conditions which are dangerous to health and 
 deprive us of ordinary comfort. Hygrometer and dew point tables 
 included in this book. 
 
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 "The Mountains of Cloudland and Rainfall." Twenty-four pages, illus- 
 trated with different types of clouds and ancient and modern rain 
 gauges. The matter of rainfall is dealt with in a very concise 
 manner. Information is given on the variety and speed of clouds, 
 with their elevation. Different specimens of clouds are described, so 
 it will be quite easy for any observer to quickly recognize them. 
 A page of "Weather Lore" fittingly concludes this interesting book. 
 10 cents postpaid, stamps or silver 
 
 "The Thermometer and Its Family Tree." Twenty-four pages, illus- 
 trated with thermometers from the time of their invention to the 
 present day. The history of the birth and development of this inter- 
 esting instrument is popularly dealt with and the different scales in 
 use on all types of instruments are clearly described. The manu- 
 facture of thermometers is described in plain language, including 
 the manufacture of the glass from which they are made. 
 10 cents postpaid, stamps or silver 
 
 "Weather and Weather Instruments." Second and Revised Edition. 
 164 pages profusely illustrated. Written in the simple, unscientific 
 language of the layman, conveying a clear idea of this absorbing 
 subject to anyone of ordinary mental capacity, even though pre- 
 viously unacquainted with so attractive a study. Chapters on 
 clouds, fogs, weather map, frost, dew, snow, rain, cyclones, barom- 
 eters, humidity, thermometers, thunder, etc., etc. 
 Cloth cover $1.00; paper cover 50c postpaid, stamps or silver 
 
 24 
 
YB 09734 
 
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 UNIX^ERSITY OF CALIFORNIA LIBRARY