LIBRARY 
 
 OF THE 
 
 UNIVERSITY OF CALIFORNIA. 
 
 .L s. c 
 
 Gl FT OF 
 
 a. 
 
 SL 
 
Lectures 
 
 ON 
 
 Building Construction 
 
 BY 
 
 Captain John Stephen Sewell 
 
 Corps of Engineers, United States Army 
 
 DELIVERED AT THE 
 
 United States Engineer School of Application 
 April Q, 10, and //, 1903 
 
 WASHINGTON BARRACKS, D. C. 
 
 PRESS OF THE ENGINEER SCHOOL 
 1906 
 
Lectures 
 
 ON 
 
 Building Construction 
 
 BY 
 
 Captain John Stephen Jewell 
 
 Corps of Engineers, United States Army 
 
 DELIVERED AT THE 
 
 United States Engineer School of Application 
 April 9, 10, and II, 1903 
 
 WASHINGTON BARRACKS, D. C. 
 
 PRESS OF THE ENGINEER SCHOOL 
 1906 
 

 
 
G. 
 
 LECTURES ON BUILDING CONSTRUCTION 
 
 *By CAPTAIN JOHN STEPHEN SEWELL 
 Corps of Engineers, U. S, Army 
 
 DELIVERED AT THE UNITED STATES 
 ENGINEER SCHOOL OF APPLICATION 
 
 APRIL 9, 10, AND 11, 1903 
 
 The fundamental principles underlying the art of building are the same 
 as those governing all forms of construction. To one well versed in the 
 principles of engineering they can present nothing new, except in their 
 particular mode of application. So much has been written and printed on 
 the art of building that it might seem superfluous, at this time, to add 
 another word. Yet, up to the present, the design and erection of buildings 
 has been a matter of tradition, precedent, and rule of thumb; but modern 
 requirements are such that it has been necessary to call in the engineer to 
 the assistance of the architect; as this is a thing of recent development, it 
 is possible that the application of engineering criteria may not only indicate 
 the way to safe and successful development of features not founded on 
 precedent, but even disclose room for improvements in the most time- 
 honored rules of practice. Architecture is a matter of tradition and prece- 
 dent; engineering is one of principles, to be well ascertained and established, 
 and then logically but fearlessly applied, whether along old lines or not. 
 
 The art of building has never been fully discussed from the engineer's 
 standpoint, and it is not proposed herein to attempt such discussion, but 
 there are a number of points resulting from practical experience which 
 will be touched upon with a view to supplementing the course in Building 
 Construction at the Engineer School. 
 
 Every military engineer should be master of construction in all its forms. 
 Probably the first really difficult structures erected by man had their origin 
 in military requirements; so, military engineering may fairly claim to be 
 the father of all construction. 
 
 Coming to buildings proper, there was not a great amount of structural 
 design in the architecture of India, Babylonia, Egypt, or Greece. With 
 the free use and great development of the arch and dome by the Romans, 
 the structural aspect of buildings became more interesting; and with the 
 development of the Gothic and related styles of architecture there appeared 
 structural skill of a high, order; to produce the wonderful effects seen in 
 
 1G9934 
 
the old cathedrals, the material was often called upon to do its utmost 
 limit of work and there was an accurate adjustment of opposing forces 
 which must always command our admiration. Yet the design was such 
 that the forces had always to be counterbalanced in a very indirect and 
 costly way. Only the religious enthusiasm of the Middle Ages and a 
 fine artistic sense, combined with the modern engineer's skill, without his 
 sense of economy, could have produced such a type of building. The 
 modern architect seems often to have inherited the artistic sense of his 
 medieval predecessor but not always his skill as a structural designer. 
 
 With buildings of the simpler and cheaper type, the engineer has not 
 often much to do; yet. they present many interesting points in construc- 
 tion, though not requiring any great amount of mathematics in their 
 design. 
 
 On the subject of frame buildings, little can be added to Part II of 
 Kidder's Building Construction and Superintendence. Some points 
 brought out by him, however, may well be emphasized. In the matter 
 of the frame, the method shown in Figure 19, page 50, could hardly be 
 improved; considering cost and efficiency together, it is probably the best 
 that can be done. The importance of having at all points the same 
 amount of timber capable of shrinking in a vertical direction can not be 
 overestimated. The lengthwise shrinkage of timber, while by no means 
 inappreciable, is not enough to cause cracks in plaster or to spoil the fit of 
 doors and windows. But its crosswise shrinkage is a very different mat- 
 ter. If one end of a partition is supported on 6 inches more of shrink- 
 able timber than the other, cracks will surely appear in time, and the fit of 
 doors will be noticeably impaired. Where inequalities in the amount of 
 shrinkable timber are inevitable, it would be well, in the case of those 
 members whose shrinkage will cause trouble, to buy kiln-dried lumber, 
 if obtainable in suitable sizes, and give it a priming coat of paint before 
 exposing it to the weather in the unfinished building. Even this will not 
 entirely cure the trouble, but it will greatly lessen it. Thoroughly aired 
 seasoned lumber would be better, but it can not always be obtained. 
 Kiln drying is of doubtful utility in large pieces; if thoroughly done, it is 
 likely to cause serious checking; if not thoroughly done, the shrinkage is 
 not taken out, and ordinary lumber might as well be used. The expense 
 of kiln drying large pieces would also be prohibitive in most cases. A 
 certain amount of shrinkage and a few cracks in a frame building are 
 probably inevitable. 
 
 The method shown by Kidder for the support of an interior partition, 
 in Figure 62, page 80, is one of the few mistakes in his Part II. Parti- 
 tions weigh a good deal themselves, and often support floors above. To 
 
depend on the holding power of a lag screw under a direct pull is not 
 safe; besides, it seriously weakens the joists at the most vital point. 
 
 In many cases, where shrinkage and settlement are feared, an interior 
 partition might be built as a truss, so as to carry itself, from end to end, 
 and thus be independent of the floor joists beneath it; but probably the 
 end supports, in a frame building, would be as liable to settlement as the 
 joists. A reasonable amount of care and money expended upon fire and 
 vermin stops is a good investment The underside of girts and partition 
 caps might well be covered with tin, where they are exposed between the 
 studs. This will prevent fire from attacking these members until the 
 temperature has become quite high; it will also entirely prevent vermin 
 from weakening them by gnawing. A rat will easily gnaw through a 
 piece 4 by 4 inches, if he can get at the wood. 
 
 In addition to the tin underneath, it is well to use brick nogging above, 
 so as to prevent the horizontal passage of fire and vermin from one room 
 to another between the floor and ceiling. 
 
 The roof, even of a frame building, is much better covered with slate 
 or tin than shingles, so far as mere utility is concerned. Sparks from 
 chimneys and neighboring conflagrations are much less liable to set the 
 house on fire, and slate, at any rate, will last much longer than shingles. 
 On the other hand, shingles can be used rt> obtain effects that are very 
 attractive, and in isolated houses the fire risk is not a fatal objection to 
 their use. Economy often compels it. 
 
 A slate or tile roof, because of its permanence, is worthy of copper flash- 
 ing; but a shingle or tin roof should be flashed with tin. The best grades 
 of I C plates should be used for this purpose. In any case, the flashing 
 must be done with the utmost care; rain and snow are thorough inspectors; 
 if there is a defect in the flashing they will surely discover it and announce 
 the fact in the form of ruined ceilings and falling plaster. Gutters also 
 must be well designed and carefully built. In latitudes where there is 
 much real winter, the best forms of gutter are those shown in Figures 129 
 and 142, Kidder's, Part II. In these forms the freezing of the gutter can 
 never cause water to back up under the roofing and appear inside of the 
 house. 
 
 Chimneys in frame houses must always be so constructed that relative 
 shrinkage or settlement between them and the house can not strain either 
 structure or impair the flashing. No part of the brickwork should project 
 over or have a bearing on any part of the timber construction. The 
 chimney should be a separate and self-contained structure, including the 
 fireplaces, but not the hearths, from the ground up. 
 
 When buildings have brick walls, timber floors, and timber partitions, 
 
a certain inequality of shrinkage is generally inevitable. Partition caps 
 and girders are bound to shrink; so are floor joists. The brick walls will 
 shrink if they are laid up in lime mortar, but the amount of shrinkage 
 varies in different cases and can not be predetermined. If the walls are 
 laid in cement mortar, as they should be in all Government buildings of 
 any importance at all, the shrinkage of the masonry will be negligible. 
 Assuming that the walls will not shrink appreciably, the problem is pre- 
 sented of preventing shrinkage elsewhere from throwing floors out of 
 level, spoiling the fit .of doors and producing unsightly cracks. One 
 method is to make all partitions that are continuous from the foundation up 
 of brick ; but this is often impossible because of expense. Even if this is 
 done, there will be other partitions that must be supported by the floors ; 
 the only sure remedy, in this case, is to use a steel beam to carry the par- 
 tition. In the case of the partitions that are continuous from the founda- 
 tions up, serious shrinkage can be prevented by building them of brick to 
 the first floor, and of studding above, provided the studs start from the 
 bricks in the first story and are supported always on the partition caps 
 above. If these caps are of timber there will be a little shrinkage, but 
 they might be made of two steel angles forming a sort of inverted channel, 
 and secured to the tops of the studs, in each case; the upper studs could 
 be secured to the caps by lu$s or clips. All shrinkage that would do any 
 harm could be eliminated by supporting all partitions and the ends of all 
 floor joists on a system of steel girders and beams supported in turn by the 
 brick walls. 
 
 If any of the methods mentioned above are applied with thoroughness, 
 the cost of the building will be materially increased. In the case of any 
 building small enough to justify the use of studded partitions at all, the 
 same result could be attained, at a cost slightly greater yet, by making the 
 floors of reinforced concrete and omitting wooden joists altogether. This 
 would make the building practically fireproof, and in all cases where it is 
 likely to be permanent, even if it is only a set of quarters, this construc- 
 tion should be adopted if sufficient funds are available. Where the walls 
 are of brick, the conditions are favorable for trussed partitions, transferring 
 their load to their ends. If firepoof floors and steel beams are both out 
 of the question, much can be accomplished by trussing the partitions, even 
 if some of the end supports are timber struts, since the endwise shrinkage 
 is of small importance. If well-seasoned timber girders happen to be 
 available in sufficient numbers, they can be used for the support of parti- 
 tions and floor joists and will greatly lessen shrinkage cracks. In any 
 case, every reasonable precaution should be taken to prevent or lessen 
 these cracks; while not dangerous to the structure, they are unsightly and 
 
are a refuge for vermin. If a brick house -is not furred on the inside, the 
 angle between a brick wall and a studded partition should be lathed with 
 wire cloth or expanded metal, or cracks will surely appear. 
 
 Fire and vermin stops are just as important in a brick house as a wooden 
 one. The most effective form is a fireproof monolithic floor, stretching 
 unbroken from wall to wall. But much can be done by treating studded 
 partitions in the manner suggested for frame houses; and if the walls are 
 furred on the inside the brickwork should be corbeled out as far as the 
 finished plaster surface, from a point one course below the joists to a 
 point one course above them. In all cases, hot-air flues in studded par- 
 titions should be made of bright tin or galvanized iron and kept at least 
 1 inch away from neighboring studs and joists, which should be cov- 
 ered with tin where the flue passes near them. The lathing over the flue 
 should be of wire cloth or expanded metal. 
 
 The roof of a brick building should always be of tile or slate, if possible. 
 If, however, the roof has a very flat slope, and in any case if money is 
 not abundant, some form of sheet metal is more suitable and is very 
 generally employed. 
 
 The metals available for roofing are tin plates, copper, zinc, and lead. 
 Copper and tin are the only ones that are commonly employed in this 
 country. Zinc is said to be used a good deal in Belgium, and many 
 European nations have used lead quite extensively. It is doubtful 
 whether there are any mechanics in the United States thoroughly 
 competent to work in either zinc or lead. 
 
 Copper, besides being very expensive, has a very high coefficient of 
 expansion and contraction, and invariably gives trouble. It requires 
 attention all the time on this account. No matter how much allowance 
 is made for expansion and contraction, it appears sooner or later where 
 not expected, and is a continual source o'f leaks. However, if the neces- 
 sity for frequent inspection and small repairs is accepted, a copper roof is 
 very durable and permanent, and is not by any means to be condemned, 
 if there is money to pay for it. Copper is probably the ideal material for 
 flashing. As it is used for this purpose in small pieces, usually not 
 soldered together, temperature changes are not a source of trouble. Cop- 
 per for roofing and flashing should be hot rolled, so as to be soft, and 
 should weigh not less than 16 ounces per square foot. For important 
 work, where expansion stresses can be well provided for, it would better 
 weigh 20 ounces per square foot. Where copper is used for gutters and 
 spouts it should be cold rolled and weigh not less than 16 ounces per 
 square foot; 20 ounces is again preferable, if expansion troubles can be 
 obviated. Copper is sometimes pressed into shapes resembling roofing 
 
6 
 
 tiles, and when used in this way is very durable and gives no trouble from 
 temperature changes. It should be cold pressed so as to be as stiff as 
 possible. 
 
 Tin roofing plates consist of sheets of black iron, dipped in a molten 
 mixture of lead and tin. The best plates are made by a process known 
 as the hand-dipped palm oil process, or, sometimes, as the "old method." 
 The plates are pickled, thoroughly cleansed and annealed, dipped in an 
 oil expressed from the seeds of a certain variety of African palm, and then 
 dipped in the mixture of lead and tin. The best grades are not submitted 
 to any further process, except sorting and packing. Inferior grades, after 
 dipping, are run through rolls, which reduce the coating to a minimum 
 thickness. Great skill is required in dipping to secure uniform distribu- 
 tion of the coating; when this is accomplished, and the plates are not 
 subsequently rolled, the thickness of the coating and therefore the dura- 
 bility of the plate are a maximum. In some plates of an inferior grade, 
 acid is used instead of palm oil, to secure adhesion between the plates and 
 the coating. The use of acid, and the rolling of the plates after dipping, 
 are devices for lessening their cost, and, in this case at least, their efficiency. 
 The only really cheap tin plate is the best, when ultimate economy is in 
 view. 
 
 Tin plates come in two weights, known as I C and 1 X. The differ- 
 ence in weight is in the iron, and not in the coating. I C is the lighter 
 weight and is usually used for roofing; I X is heavier and is used for 
 flashing, for gutters, and for spouts. Tin plates also come in two sizes, 
 14 by 20 inches and 20 by 28 inches. For roofing, the smaller size is 
 more expensive to lay, but is also preferable, because it provides more 
 thoroughly for expansion. All good tin plates are stamped with the 
 name of the brand and the maker. A box contains 112 sheets; it should 
 weigh 120 pounds if of 14 by 20 inch, and 240 pounds if of 20 by 28 inch 
 plates. The total weight of coating in a box of the best 14 by 20 inch 
 plates is about 20 pounds, of which 6 pounds are tin and 14 pounds are 
 lead. It would probably be possible to get as much as 30 pounds of coat- 
 ing on a box of 14 by 20 inch plates, but the process would be very slow 
 and more expensive than it is worth. Plates coated with tin and lead are 
 known as terne plates ; if coated with tin alone they are called bright 
 plates; the leading manufacturers claim that bright plates are not as durable 
 in a damp climate as terne plates, and probably the claim is well founded. 
 After the plates are coated they have to be carefully sorted, as there are 
 always some defective ones. These may carry the full weight of coating, 
 but have it unevenly distributed, in which case they are not as good as if 
 they had less coating uniformly distributed. The defective plates result- 
 
ing from the manufacture of any brand of high-grade terne plates are 
 known as the -'wasters" of that brand. 
 
 In the matter of using the plates, a standing seam roof is preferable, if 
 the pitch is steep enough. Painting on the underside before laying, and 
 on the outer surface after laying, should not be neglected. The state- 
 ment often made that the roof should be allowed to show slight signs of 
 rust before painting on the outer surface had its origin in ignorance, if in 
 nothing worse. One good coat on the underside is usually considered 
 sufficient; but two would be better. No waterproof paper or felt should 
 ever be used under a tin roof, as this would promote condensation and 
 rusting out of the metal from the underside. Acid should never be used 
 as a soldering flux, whether for tin or copper. Copper should always be 
 tinned where it has to be soldered; this is necessary to produce the requi- 
 site adhesion between the copper and the solder. The tinning need be 
 done, of course, only over the small surfaces to which the solder must be 
 actually applied, and is often done at the site of the work by the mechanics 
 themselves. All soldered joints in copper work must be made very heavy 
 with solder; even then they will almost inevitably open, sooner or later. 
 
 Waterproof felt is much used both by itself and in connection with 
 other materials for the weather finish of roofs. Used by itself, laid 
 a slight lap and fastened with nails and tin washers, it is very suitable 
 for temporary buildings, sheds, workshops, etc., and is very cheap. It 
 may be swabbed where it laps with a waterproof cement, which will 
 add to its efficiency and prevent rain from driving up under the lower 
 edges. Laid in several thicknesses, with heavy swabbing coats between 
 the layers, it forms a very durable and satisfactory roof finish. It 
 can be further covered with gravel or tile, laid in waterproof cement 
 or mastic, and in the case of the tiles, with all vertical joints grouted 
 with Portland cement. A roof finish like this, where appearance is 
 not important, is good enough for any building. It is practicable only 
 on comparatively flat roofs, though the tile can be used on slopes as 
 steep as iV. The best and most durable felt is made entirely of 
 wool, and saturated with some refined asphalt which will not rot in 
 contact with water, nor dry out in the sun. "Trinidad asphalt is not 
 suitable for this purpose. Of asphalts available in this country, 
 Alcatraz and Bermudez are the best. They should be softened with 
 enough residual oil from the distillation of petroleum to give them 
 the necessary fluidity, but no more. An asphaltic cement for use 
 with this felt is made of the same material as the saturating com- 
 pound; if it is to be applied hot, it is made quite stiff. But by mix- 
 ing the compound with naphtha or benzine, it can be made fluid 
 
enough to apply cold; the evaporation of the solvent leaves a thin 
 uniform coat of the compound, which will preserve its. flexibility and 
 waterproof qualities for a long time, if not subjected to mechanical 
 injury. 
 
 Tarred felt, and swabbing coats of coal tar, are more commonly 
 used than asphalt felts and cements. But coal tar is so devitalized by 
 the extraction of the components useful for the manufacture of aniline 
 dyes, perfumes, flavoring extracts, etc., that the part of it that finds 
 its way into the market in tar papers and felts lasts but a short time; 
 moreover, tar felts and papers nearly always contain much vegetable 
 fiber, which is not nearly so durable as wool. Asphalt felts and 
 cements cost only a little more, and should always be used. 
 
 There is a felt in the market, known as Paroid, manufactured by 
 F. W. Bird & Son, of East Walpole, Mass., which the makers claim 
 is a pure wool felt, saturated with Alcatrez asphalt. If this is true, it 
 is as good a felt as can be made. There are several brands that are 
 saturated with Trinidad asphalt, but they are hardly better than good 
 tarred felts. The makers of the Paroid roofing felt, not only saturate 
 the felt with their asphaltic compound, but also coat it on both sides 
 with their liquid cement, which they sell under the name of Parine 
 cement liquid. They further roll a dusting of powdered soapstone 
 into both surfaces, to prevent the felt from being sticky. 
 
 In addition to copper and tin, corrugated iron, both black and gal- 
 vanized, is often used for roofs; but it is not cheap it is ugly, and 
 possesses no advantages except for permanent shops where it is desired 
 to fasten the weathering of the roof directly to the steel framework, 
 without fire protection of any kind. 
 
 In the use of all sheet metal roofs, great care must he taken to pre- 
 vent the wind from taking off the metal covering. Corrugated iron 
 must be very firmly fastened down, for it is not practicable to keep 
 the wind from under it. Copper and tin roofs must be turned down 
 at the eaves and closely tacked along the edges, or, in some cases, 
 soldered to the gutter, to prevent the wind from getting under it. 
 Otherwise, a violent storm will roll it up, pulling the nails as it goes, 
 and end by stripping the entire roof covering off, in an astonishingly 
 short time. 
 
 Of the various forms of roof covering described, copper and the 
 tiles laid on an asphalt base are really too expensive for non-fireproof 
 buildings; of the others, a simple felt, of single thickness, without 
 a swabbing coat, is the cheapest. In a general way, shingles come 
 next, then tin, and then slate or roofing tiles. The latter, when used 
 
UNIVERSITY fl 
 7 
 
 9 
 
 in highly ornamental forms, may be very expensive, but are often used 
 in non-fireproof buildings of a high class for architectural effects. 
 
 So far, only those points have been touched upon which pertain 
 peculiarly to such buildings as ordinary dwellings, whether of wood 
 or brick. Many other matters, such as paint, plumbing, heating, 
 hardware, dampproofing, quality of finish, lighting, etc., are of 
 importance, but must be discussed in connection with fireproof work, 
 and can then be best discussed for all classes of buildings. Before 
 leaving the subject of non-fireproof buildings, however, a few points 
 should be brought out relative to mill construction, or, as it is some- 
 times called, slow-burning construction. This is quite sufficiently 
 well described in current literature, and complete general specifica- 
 tions for its design can always be obtained by simply addressing a 
 request to Mr. Edward Atkinson, of Boston, Mass., who was largely 
 instrumental in introducing it, and has a missionary's zeal in dis- 
 seminating information in regard to it. This construction has for 
 its most essential points the use of none but large timbers and the 
 avoidance of all cellular or hollow construction, such as studded par- 
 titions, covered with either plaster or matched boarding. It neces- 
 sarily involves the use of iron or steel post caps, joist hangers, etc. 
 A great variety of these devices can be had in stock, guaranteed by 
 their makers to be safe under specified loads. The main point is 
 that these guarantees are usually worthless. Every engineer who 
 adopts mill construction must use them, but he should carefully calcu- 
 late their strength against shearing and bending at every point, for 
 many current designs are produced by mere rule of thumb and are 
 fatally weak at some point. Another thing about mill construction 
 is that it is not slow burning at all; it might be very properly called 
 slow igniting, for that would be a truthful description. Large 
 timbers are slow to ignite, and with every nook and corner open to 
 view, there is much less probability of a fire starting and getting be- 
 yond control before discovery; combined with a thorough automatic 
 sprinkler installation, a mill construction building is comparatively 
 safe from destruction by fire. But once a fire gets a fair start in it, 
 it is doomed to certain and speedy destruction. There are long lists 
 of such catastrophes, such as the destruction of the Capital Traction 
 Company's power house at Fourteenth and E streets, in this city, 
 some years ago. It usually takes from thirty minutes to an hour for 
 the complete destruction of a four to six story building occupying 
 an entire block. One reason probably is that no available timber but 
 long leaf pine can be secured in sufficiently large sizes at a reasonable 
 
10 
 
 price. Once fairly started, it burns with almost explosive violence, 
 and nothing can save it. The people who live in the long leaf pine 
 belt never use this timber in their stoves, if they can help it, because 
 it burns so furiously it soon destroys the stoves, besides making a 
 proper control of the temperature, whether for cooking or heating, 
 quite out of the question. 
 
 One point that should never be neglected in any brick building, 
 with timber floors, is the cutting of the wall ends of girders and 
 joists on a bevel, to prevent throwing the wall by the breaking of the 
 joist or girder when burned through in a fire. Anchors in such cases 
 should be fastened near the bottom of the beam, preferably with one 
 large bolt, just inside the wall line. Then, when the beam falls, 
 even if it hangs by the anchor, it can freely revolve downwards with- 
 out bringing any leverage on the walls. Where the load of a joist 
 or girder does not require bearing plates or templates to distribute 
 the pressure, the course immediately under the beam should be a header 
 course, otherwise severe shocks and vibrations might cause the bricks 
 to loosen and slip out of the wall. Major Abbot observed, after the 
 Charleston earthquake, that this was a very vital point. Where the 
 ends of the joists rested on header courses, they invariably remained 
 in place, tut very often, where the joists rested on a stretcher course, 
 the bricks slipped out and allowed the floors to drop. 
 
 There are some advantages in corbeling out a shelf to receive the 
 ends of joists, provided the corbeling is not objectionable on artistic 
 grounds, and is well done. It should project about 1 inch to a 
 course, be made entirely of headers, and be only wide enough to give 
 the requisite bearing. On the whole, however, in a well-built wall, 
 it is better to let the girders and joists project into the wall, leaving 
 a small space on the sides and top for ventilation. This insures 
 greater unity of the structure, and applies the load nearer to the 
 center of the wall. If heavy loads call for templates or bearing 
 plates, it is better to put them entirely within the wall, at least 2 
 inches back from the face, to avoid concentrated pressure at the inner 
 edge. It is also well, in such cases, to support the- end of the beam 
 on a small plate in the center of the bearing plate or template, to 
 prevent deflection in the beam from disturbing the distribution of 
 pressure. It is to be observed that the usual method of reducing the 
 thickness of the wall as the upper stories are reached, by dropping 
 off half a brick at a time on the inside, has a beneficial effect in 
 counteracting the eccentricity of the floor loads; corbeling always 
 increases this eccentricity, and that alone should condemn it, where 
 
11 
 
 very heavy loads must be carried. It seems entirely possible, and even 
 probable, that advances in fireproof construction will, before long, 
 displace mill construction in all important factory buildings. While 
 this is a consummation much to be desired, mill construction has 
 played an important role, and will always be looked upon as a long 
 step in advance, taken at a time when there was urgent need of it. 
 
 FIREPROOF BUILDINGS 
 
 It is in buildings so large and important that carrying the weights is a 
 serious matter, and fireproof construction is considered necessary, 
 that the civil engineer first becomes indispensable. Many of the 
 improvements in design, and execution introduced by him in such 
 structures, are applicable also to the smaller, non-fireproof buildings 
 and if applied would produce much better results than those com- 
 monly attained, without increase of cost. Where such points are 
 brought out, their application to less important buildings will be indi- 
 cated. 
 
 The first question in any building is the plan. This is mani- 
 festly determined by the uses to which the building is to be put, and the 
 space within which it must be confined. It must be so arranged as 
 to be fit for its purpose, yet not inconsistent with a suitably artistic 
 treatment of the elevations. Right here is where the architect, en- 
 gineer, and owner often clash. Architects lay great stress upon the 
 plan, and are very jealous of their jurisdiction over it. This is quite 
 natural, for a poor plan may make good architectural treatment im- 
 possible; yet, the architect is apt to lay undue stress upon the artistic, 
 and to overlook, neglect, or deliberately sacrifice convenience and 
 utility. The engineer and owner are apt to consider the latter points 
 first, and not to give due consideration to the former. 
 
 As an example of what the architect will do, if unrestrained, one 
 of the most prominent architects of Washington, in making plans 
 for a hospital building recently, located the dumb waiter 40 feet 
 from the kitchen, and stopped it off at the third floor, although there 
 was a ward on the fourth floor, designed for thirty or forty patients. 
 How they were to be fed, and the directness of the service to all the 
 floors, were not considered at all. The fact remains, however, that 
 in the majority of cases, the architect should make the plan; but he 
 should be compelled to change it, if necessary, until it not only satis- 
 fies the artistic requirements, but the utilitarian ones as well. There 
 is always some solution reasonably good, from all points of view, and 
 
12 
 
 if the engineer has any control at all, he should see to it that this 
 solution is finally worked out. Making floor plans for buildings is 
 not a simple matter not even for a small dwelling. It should re- 
 ceive the most careful consideration from all concerned, if the highest 
 efficiency is to be attained. 
 
 The floor plans having been fixed, the architect will soon have the 
 elevations, in skeleton form, at least, for these must be considered, 
 along with the plans, before the latter can really be fixed. With the 
 plans and preliminary elevations, the engineer is ready to begin, in 
 some detail, his own peculiar work. The floors and interior parti- 
 tions always, and the exterior walls generally, in a modern building, 
 will be carried by the framework, which is usually of steel. The 
 first task is to locate the columns. This has to be done with a view 
 to the interior subdivision and finish, as a matter of course. Next 
 must be considered the system of girders and beams by which the 
 floor loads are carried and finally concentrated at the columns. Then 
 the loads imposed on the columns at each floor must be calculated. 
 They should be divided into live and dead. The former comprises 
 the entire superimposed floor load, and the latter the weight of con- 
 struction. The dead load can not always be calculated accurately until 
 two or three preliminary designs have been made, since the design 
 itself determines part of the dead load. It is possible to assume 
 quite closely what the dead load will be, however, for a given class of 
 building, and usually one preliminary design and one corrected one, 
 will be sufficient. Having the column loads, the foundations can 
 be designed. If the external walls are not carried on the framework, 
 they will still start from the same foundations as the wall columns 
 and thus their weight must be carried at the bottom just the same as 
 if it were part of the column load proper. Where a building is of 
 moderate height and has heavy walls, no steel columns need be used; 
 the ends of girders and beams would be borne by the walls, and thus 
 the floor loads would go from the outer bearings of girders and beams 
 to the exterior foundations through the walls themselves. But the 
 foundation problem would not be essentially different from that pre- 
 sented by a building with steel wall columns, carrying either the 
 floors alone or both the floors and the walls. 
 
 In designing the foundations, the first requisite is a knowledge of 
 the nature of the strata upon which they are to rest. Certain and 
 definite knowledge upon this point is difficult and often expensive to 
 obtain. If some engineer or physicist could devise a reasonably simple 
 system whereby from physical analysis of a soil its power to carry 
 
13 
 
 loads could be predicted within 100 per cent., he would earn the 
 gratitude of all future generations of engineers. It is not in the least 
 likely that this will ever be accomplished. 
 
 There are various ways of securing information as to the strata 
 underlying a proposed structure. Borings are the -most obvious, as 
 well as the quickest and cheapest of all methods yielding results of 
 any value. But even borings are very deceptive; they often miss 
 the vital and controlling feature of the whole situation, even when 
 very close together. Actual "excavations or test pits carried to sub- 
 grade, or deeper, are better than borings, and more expensive. Only the 
 excavation of the foundation trenches or pits themselves will disclose 
 the whole truth, and even they often fail to reveal it all. When the 
 structure is of any importance, the excavation should be carried to 
 sub-grade, over the entire area probably required for foundations, then 
 borings and occasional pits should be carried still deeper, and full- 
 sized tests of the bearing power should be made, if possible. 
 
 The object of the foundation is to so distribute the weight of the 
 building and its contents to strata in position that there will either 
 be no settlement at all, or, if there must be settlement, that it shall 
 be uniform. If there is any hope of limiting the settlement to zero 
 or to a negligible quantity, it should be done, even at a considerable 
 expense. A poor superstructure will stand a long time on a good 
 foundation; but no sort of superstructure can stand intact on a poor 
 foundation. Therefore, it is better to make the foundation good, 
 even if it has to be done by skinning down what goes on top of it. 
 
 Of the various materials likely to be met in constructing foundations, 
 solid rock, gravel, hard pan (i. e., a consolidated mixture of clay, 
 sand, and gravel), beds of bowlders, and reasonably coarse clean sand 
 need never give any anxiety, provided there is nothing soft beneath 
 them. They will all carry loads of from three to fifty tons per square 
 foot with perfect safety. A load of from three to six tons per square 
 foot will always result in footings of a reasonable size, so there is no 
 need of extravagant designs. Of the materials named, sand is the 
 only one that calls for much investigation; yet it would be well always 
 to build an experimental pier like the probable footings, and load it 
 if possible, until settlement begins. Such tests should last for several 
 days, at least, as the yielding of some soils is very gradual, but, un- 
 fortunately, none the less certain. 
 
 It is generally assumed, no doubt correctly, that when pressure is 
 applied to a certain area of the top surface of a given stratum, it 
 spreads laterally as it is transmitted downwards, so that the successive 
 
14 
 
 areas which feel its effects become constantly larger. The angle of 
 spread for a given material can not be certainly determined. It will 
 be seriously modified if adjacent areas at the surface are also loaded; 
 let it be denoted by 0, and be measured from vertical planes through 
 the edges of loaded area at the surface; let it be considered positive 
 when it is really an angle of spread. It is possible that may be 
 reduced to or perhaps even to a negative value, by reason of adjacent 
 surface loads. In the latter case, it is almost certain that the bearing 
 power would be exceeded, and there would be settlement over the 
 entire surface of all structures, both old and new. Sometimes the 
 strata near the surface are able to bear the superimposed loads, and even 
 though there are weaker strata below, may have such a value that 
 the pressure is distributed over a sufficient area of the softer lower 
 strata, to enable them also to carry it. This is true for an isolated 
 structure. If other adjoining structures are erected afterwards, the 
 area of the softer strata available for carrying the first structure will 
 be diminished, and settlement of both old and new works may follow. 
 In the case of a mortar battery built by Major Abbot at Charleston, 
 the overlying stratum was sand, and it was about 10 feet thick. It 
 bore on small areas, unit pressures at least as great as those due to 
 the battery, without a sign of settlement. But when the larger area 
 occupied by the battery was loaded, settlement followed to the extent 
 of 2 feet and some inches. The necessary precautions for securing 
 uniform settlement were observed, however, and the structure reached 
 its final level without serious cracks or damage. To illustrate the 
 principle involved, suppose that has such a value in a given case 
 that the pressure has spread 2 feet all around when it reaches the soft 
 lower stratum. Suppose a test load on the surface is applied to an 
 area 1 foot square. It will spread over an area at the lower stratum 
 bounded by a figure consisting approximately of a square 5 feet on a 
 side, with its corners cut off by quadrants tangent to the sides, having 
 a radius of 2 feet, and centers located on the diagonals of the square. 
 This area will be about 21 square feet. Now suppose that the area 
 at the surface is 10 feet square. The area below, even if the corners 
 are not rounded off, will be only 14 by 14, or 196 square feet 
 not twice as much as the surface area, whereas in the other case, it 
 was twenty-one times as much. The conditions illustrated here may 
 occur on city blocks, as the city becomes more closely built, and new 
 structures are erected in juxtaposition to existing ones. If the softer 
 lower strata are compressible, settlement of both old and new works 
 may follow. On the other hand, if the soft strata are saturated with 
 
15 
 
 water, they will be incompressible. Settlement will then be impos- 
 sible, unless the material can escape laterally or both laterally and 
 vertically. If the whole of a large area is loaded, bdth of these things 
 may be prevented, and the load will be carried on the same principle 
 as the pressure on the piston of a hydraulic jack. The condition is 
 one of unstable equilibrium, however, and is not by any means 
 desirable. Strata that are soft and filled with water, act partly like 
 liquids and partly like solids. If they are loaded vertically, and can 
 not yield laterally, they may bulge up around the loaded area, causing 
 settlement of the latter. This can be prevented by properly loading 
 the areas likely to bulge up; but just what load per square foot will be 
 required and how much of the adjacent area must be loaded would be 
 difficult to determine in any case, and must be largely a matter of 
 judgment and experience. 
 
 In testing soils, it should be remembered that when only a small 
 area at the surface is tested, the pier or post used for applying the load 
 will often have a sort of punching effect and begin to settle under 
 unit loads which would be perfectly safe over large areas. Sand, with 
 water in it, will slip out from under a test pier or post, and the test 
 load will work downwards when it does not amount to 10 per cent, 
 of what the sand would carry under an actual structure. It is evident 
 from all that has been said that the results of tests on the bearing 
 power of soils must be used with judgment. The very same results 
 might follow from a given method of testing in soils of widely vary- 
 ing bearing power. 
 
 It is useless to add in this paper anything on the ordinary methods 
 of increasing the bearing power of a compressible soil. They are all 
 thoroughly described in current literature. It might be useful to say, 
 however, that when tests show manifest compression of the surface 
 strata, under loads approximating those desired to be used in practice, 
 it is better to adopt some mode of treatment at once. The same is 
 true of unyielding strata overlying soft ones, unless the thickness of 
 the former is sufficient to guarantee the load against breaking through. 
 
 If it is decided to use wooden piles, they must be cut off below 
 the water line, to insure permanence. If this is inconvenient or 
 expensive, concrete piles may be used, which do not depend upon the 
 condition of the soil for their durability. Great progress is being 
 made in the use of concrete piles or piers put down like piles. All 
 the student officers should observe and make notes of the method now 
 in use at the site of the officers' quarters for the Engineer School, 
 as it is a very simple and economical one scarcely more expensive 
 
16 
 
 than wooden piles. The conditions here are as follows: A fill of 
 from 10 to 14 feet of argillaceous material, settling seriously under 
 loads of from 500 to 1,000 pounds per square foot; a firm stratum of 
 sand below the fill, of unknown depth, but certainly good for the loads 
 likely to be brought upon it by the officers' quarters. If wooden piles 
 were used, they would surely decay, for the fill is sometimes wet and 
 sometimes dry. Nothing would be gained by driving them and cut- 
 ting them off at the level of the water line, for this would carry the 
 excavation to the firm sand, which can carry the load without piles. If 
 the excavation were carried to the sand, it would be quite expensive, 
 and would necessitate a very large mass of concrete to bring the foun- 
 dations up to the basement floor levels. By the use of concrete piles, 
 the weight can be transferred to the sand at much less expense, and 
 there is no doubt as to the durability of the piles. In this case, the 
 piles clearly act as columns, deriving some lateral support from the 
 surrounding earth, but transmitting their loads by direct compression, 
 nevertheless. It often happens, however, that a pile driven fairly deep in 
 very soft material will carry a heavy load, without reaching a firm bear- 
 ing at all. A group of piles, in such material, will often carry a load 
 that would sink out of sight if distributed directly over the area 
 occupied by the piles. Just why this occurs is a little obscure; it is 
 not certain that it could always be duplicated. In a case of this sort 
 on the river front of New York, as nearly as the writer can remember, 
 as it was related to him verbally, an average of one pile to a certain 
 number of square feet, driven in the mud, but not to a firm bearing, 
 had been carrying a certain load per pile for a long time. It was 
 decided to increase the size and weight of the superstructure, and to 
 provide for it, more piles were driven between the old ones, but when 
 the new and heavier load was applied, the entire piled area settled 
 quite seriously. 
 
 Apparently the piles distribute the load by skin friction throughout 
 a certain volume of the materials. It will stand, when reinforced in 
 this way, a certain amount of stress without deformation, but beyond 
 this it is not possible to go. Some very remarkable statements as to 
 the bearing power of piles when driven in what seemed almost liquid 
 mud can be found in Patton's Foundations. There is some law here, 
 quite obscure and unknown at present, which would be very valuable 
 if fully disclosed. Possibly the piles tie together a large volume of 
 the soft material, compelling it to act as a unit, giving it strength 
 against deformation, and at the same time making available a sort of 
 buoyancy that it must have in its semi-liquid surroundings. At any 
 
17 
 
 rate, piles that have been settled into place under the mere weight 
 of the ram, have, after a few days, borne loads ten or twelve times as 
 great as the ram, without further settlement. This seems almost in- 
 credible, but is apparently true,. It would hardly be safe practice to 
 count on it, however, without tests in each individual case. 
 
 As a rule, the most suitable material for foundations is concrete. 
 This material, when tested to destruction under compression, gen- 
 erally fails by shearing along planes making an angle of about 30 
 with the direction of the applied force. Holes punched through 
 slabs of concrete generally increase in size as they pass through, at 
 about the same rate. It is well to spread concrete foundations at the 
 same rate, as by this means all tensile stresses will be avoided. This 
 leads to rather heavy foundations, but it is certainly safe practice, and 
 none too good for important buildings. It should be remembered 
 that, regardless of unit pressures, every wall should have a footing 
 appreciably wider than itself to insure stability. 
 
 In commercial office buildings, where settlement is expected, it is 
 customary to proportion the footings under different parts of the 
 buildings according to the dead load alone. But in important Govern- 
 ment buildings the foundations should first be made secure against 
 settlement, if possible, and then proportioned everywhere for the 
 total load. The live load will not be as likely to produce settlement 
 as a dead load of the same amount. If settlement is inevitable, a 
 grillage over the entire site stiff enough to resist distortion under the 
 varying concentrated loads of columns and piers is the best solution, 
 but it is very expensive. The next best plan is to find out what the 
 average actual total load will be, and proportion for,this. Where the 
 live load is considerable and subject to much variation, it would be 
 very hard to hit upon any method that would insure uniform settle- 
 ment, short of preventing settlement altogether. 
 
 If steel beam grillages are necessary to spread the pressure under 
 columns and walls over a sufficient area, they should be kept above the 
 ground water level if possible, and very carefully and thoroughly bed- 
 ded in Portland cement concrete to avoid corrosion. The best plan is 
 to avoid the use of beams altogether, if possible. 
 
 Within recent years foundations carried to the solid rock by means 
 of pneumatic caissons have been used in some important buildings. 
 In several cases in New York, where it was desired to have several 
 stories of cellars below the water line, the entire site has been sur- 
 rounded with rectangular caissons, separated from each other by guid- 
 ing angles, forming a pocket between the caissons. The caissons 
 
18 
 
 were filled with concrete, and the pockets were rammed full of clay 
 puddle; the bottom of the excavation was pumped out, floored with 
 concrete, and a layer of waterproofing, and then -enough more con- 
 crete to resist the upward pressure of the water. In this way immense 
 volumes of storage space have been made available at depths of 20 or 
 30 feet below the water line. 
 
 One troublesome class of operations often encountered in founda- 
 tion work is the underpinning of existing structures. In Kidder's 
 Building Construction, Part I, and in other works, many methods 
 are shown for temporarily supporting the old structures while the new 
 work is going in under them; but the most interesting and difficult 
 part of the whole operation is getting the temporary supports in with- 
 out allowing the old work to settle or collapse. On this point very 
 little is to be found in current literature. It is necessary to put in the 
 temporary supports so that they will not interfere with the new work 
 nor be disturbed by it. This often involves an excavation close up 
 to the old structure and extending some distance below it. The 
 trouble is to avoid settlement of the old work while this is going on. 
 In material not full of water, the excavation can be safely accom- 
 plished by means of cases, similar to those used in military mining, 
 but modified according to circumstances. If the excavation seems 
 too dangerous, piles may be driven at the points where the ends of 
 needles are to be supported; if it will not do to drive them with an 
 ordinary ram, they can be screwed in or sunk with a water jet. There 
 is a patented method of supporting an old wall during underpinning 
 which consists in cutting slots in it, setting up in them piles made 
 of iron pipe, and forcing the latter down with jacks working between 
 the tops of the piles and the masonry above. This operation is con- 
 tinued until it is evident that the piles are able to carry the load without 
 further settlement. The space between the tops of the piles and the 
 masonry can be filled up with iron blocks, or otherwise, and the old 
 foundation taken out. The piles would be built into the new founda- 
 tion. The writer can not refer to work actually done by this method, 
 nor give any figures of cost. But it seems plausible where the con- 
 ditions are otherwise difficult and the work important. The cost 
 would probably be considerable. Where a wall is supported by in- 
 clined shores, these should cut into it at points not far from girders 
 and floor beams, so as to get the benefit of their lateral support. If 
 it is supported on needles, it is sometimes necessary to excavate both 
 inside and outside to get support for the needles from the level of the 
 new foundation. Sometimes, by using a long needle and allowing 
 
19 
 
 the inner end to rest on the basement floor or the earth inside for 
 some distance back from the wall, inside excavations can be avoided. 
 
 Sometimes it is necessary, not only to hold a vertical weight, but 
 also to hold a bank from caving. In such cases great care is required, 
 but no general rule can be laid down. In all cases of underpinning, 
 the engineer must consider not only what his temporary supports shall 
 be, but how he will get them in place, which is the larger half of the 
 work. 
 
 All foundations should be finished with a -dampproof course, to 
 prevent moisture from rising in the walls. The best materials for 
 waterproofing and dampproofing are asphalted wool felfs and certain 
 asphalts, which do not rot in the presence of water. Neuchatel and 
 Seyssel Rock Asphalt mastics, Alcatraz or Bermudez asphalts are all 
 reliable, when properly applied. Where the tops of foundations are 
 covered with dampproofing, it must be made so it will not squeeze 
 out under the pressure. Rock asphalt mastic can be mixed with fine 
 gravel an'd made waterproof, yet hard enough, when applied in very 
 thin layers, to withstand heavy crushing loads. On vertical surfaces 
 and in the body of concrete floors, it is better to use the felts and 
 swabbing coats of asphaltic cement, either hot or cold; the mastic 
 might crack in such places, as it is quite stiff when cold. 
 
 Having settled the question of foundations, the steelwork is in 
 order. The columns should always rest on bases of built-up steel or 
 of cast steel or iron. If of cast-iron, no part should be less than 1 
 inch thick; an inch and a half would be a better minimum. Such a 
 base should never be shallow, and should not be too economically 
 designed. It should consist essentially of top and bottom bases, con- 
 nected by ribs running in both directions across the plates. The 
 sides of the base should slope at angles of about 60 with the hori- 
 zontal certainly not less than 45. A base built up of steel can be 
 allowed to have some transverse strain, but must be so stiff it can not 
 suffer appreciable distortion. Buildjng up an efficient steel column 
 base is not so simple as it looks, and it should receive the careful 
 attention of the engineer in charge of the work in every case. Like 
 post caps and joist hangers, a built-up column base must be carefully 
 designed in all of its parts, to resist all possible local strains. 
 
 With the columns, the question of structural steel proper is reached. 
 It is customary to use, as the maximum fiber stress on structural steel 
 in buildings, 16,000 pounds per square inch. In the case of the 
 columns, this is the constant that is put into the column formulae, 
 and, of course, the actual direct stress per square inch is considerably 
 
20 
 
 less, because of the allowance for buckling. If the column is properly 
 fireproofed, however, it will be stiff enough, without any allowance 
 for buckling. It is better, in such a case, to design it in simple 
 compression i. e., divide the total load in pounds by 16,000, and 
 take the result as the area of cross section of the column in square 
 inches. What is considered proper fireproofing will be described' 
 later. In cases where buckling must be considered, the parabolic 
 formula given in Johnson's Modern Framed Structures, or Gordon's 
 formula, should be used. The straight line formula is reliable within 
 certain limits, but it gives loads much too great be}'ond these limits. 
 In considering various forms of column, it should be remembered that 
 often the entire load is directly applied to only a part of the column, 
 and must be distributed throughout the section by whatever means 
 have been adopted for tying the parts of the section together. A 
 good test of a column design is to consider whether, if used as a 
 girder, in any position, it would have sufficient strength in the web 
 members to develop the strength of the flanges; unless it has, it is 
 not an ideal design. It is not necessary to have it absolutely ideal, and in 
 most cases in ordinary practice it is not. There should be a fairly close 
 approximation to ideal conditions, however and judged by this cri- 
 terion there are a number of column sections notably, one made up of 
 angles connected at intervals by short batten or tie plates which are 
 wholly bad, and should never be used, unless they can be entirely 
 bedded in a mass of concrete. 
 
 An ideal column section considered merely from its capacity to resist 
 compression and the tendency to buckle under compression, is a 
 hollow circular cylinder; but such a column would be difficult to 
 splice and it would be very difficult to attach beam and girder brackets 
 to its sides. Every practicable column section is a compromise between 
 the extremes of ideal resistance to compression and buckling under a 
 centrally applied load on the one hand, and of facility and ease of 
 designing and applying practicable connections, on the other. Col- 
 umns made up of channels, with lattice bars or cover plates, accord- 
 ing to the load, and columns of I section built of plates and angles, 
 or of an I beam and two channels, or other equivalent shapes, are 
 among the best. 
 
 Eccentric loading must be provided for, in every case. The best 
 way to provide for it is to eliminate it, even at some expense, and at 
 the sacrifice of ideal conditions in other respects. In the case of a lat- 
 ticed channel column, which is one of the best types, if there is a load 
 on only one side of it, a seat for the girder or beam can be built in 
 
21 
 
 between the channels, so as to apply the load on the axis. Z-bar col- 
 umns, or columns of I section, can usually be set so that unbalanced 
 loads can be applied directly to the webs, thus largely eliminating 
 eccentricity. If a column is loaded symmetrically, even though the 
 loads are all applied at a distance from its axis, it is quite safe to 
 consider the total load as centrally applied. In this case, if, in the 
 use of the building, the live load should be in place on one side, 
 but not on the other, there will be an eccentric load, causing trans- 
 verse stress in the column; but the metal put in to carry the remain- 
 ing live load, will usually take care of this bending safely enough, 
 although the stresses may run up to 24,000 or 25,000 pounds per 
 square inch. Great care should be exercised in connecting heavy 
 girders of long span to the columns that carry them. 
 
 It will not do to make rigid connections in such cases, for the normal 
 deflection of the girder under its load will introduce strains in the 
 column beyond all reasonable limits. If the span of the girder exceeds 
 ten times its depth, or if it is greater than 15 feet, the equation of 
 the curve of mean fiber or, at any rate, its first differential coefficient, 
 should be deduced. From this the inclination of the curve of mean 
 fiber at the points of support can be determined. Compute the 
 moment of inertia of the column section, and find from the differen- 
 tial equations of the curve of mean fiber, what uniform bending 
 moment would cause the curve of mean fiber to take an inclination 
 at the ends at right angles to that of the girder. From this the fiber 
 stress produced by the bending can be determined. This method is 
 only approximate; it treats the columns as a beam resting on two 
 points of support, and subjected to a uniform bending moment. As 
 a matter of fact, the column is generally continuous past several girder 
 connections, and if these connections are rigid, both columns and 
 girders are partially fixed at the reaction points. However, the 
 approximation will always be on the side of safety, and if it indicates 
 dangerous stresses in the column from the deflection of the girder, 
 the connection should be so designed as to leave the girder free to 
 deflect, without sliding off. This will generally result in a bracket 
 riveted to the column, for the ends of the girder to rest upon. It 
 should be bolted to the bracket, to prevent all danger of sliding off. 
 
 The columns, in fireproof buildings, are generally made continuous 
 from bottom to top. If the increments of load at successive floors 
 are very great, it will be cheaper to splice the columns at every floor; 
 but this does not often happen, and columns are generally made two 
 or three stories high. .A column of any of the ordinary types can be 
 
22 
 
 made and kept reasonably straight and true in lengths up to 40 feet. It 
 is better to reduce the number of splices as much as possible, even if 
 the column weighs a little more, and rather high stresses have to be 
 accepted in its lower part. It is not practicable to splice columns in 
 buildings with full splices, as in the case of compression members of 
 bridges. There are two reasons for this: one is that the splices 
 would be very awkward to design and execute, and the other is that 
 they are. very expensive. When the function of the splice plates and 
 angles is reduced to merely holding the columns in line, it is neces- 
 sary that the column ends should be very accurately faced off. Just 
 how serious a matter this is may be seen from a discussion by the 
 writer in Engineering News, December 25, 1902, page 544. It is 
 sufficient here to say that to realize the full factor of safety at the 
 column splices requires a grade of workmanship not always easy to 
 obtain. This is another reason for making as few splices as possible. 
 Where a splice is to be made, the maximum economy of metal 
 would place it just at the point where the full section of the lower 
 column is first required. This would be at the bottom of floor gird- 
 ers; further consideration would point to a location at the middle 
 of the depth of the floor girders, so that the ends of the columns 
 would be in a pocket formed by girders and beams, and thus secure 
 a certain reinforcement for the splice. But practical experience de- 
 mands that the entire splice be above the tops of girders and beams. 
 This makes it possible to complete a floor of beams and girders with- 
 out waiting for the tier of columns above. When the upper columns 
 come, they can be placed and the splices riveted up without the use 
 of hanging scaffolds, which is in itself a point of enough importance 
 to more than counterbalance any saving in metal effected by placing 
 the splice lower down. The column bearing can be more readily in- 
 spected, and the work on the splice, being more accessible, will be 
 better done. If a floor of beams and girders is not complete without 
 the upper tier of columns, a multitude of details of other work will be 
 delayed thereby, and this again is in itself a sufficient reason for 
 locating the splice as herein recommended. 
 
 In specifications for columns, it would be well to require that the 
 ends be faced off true to within 1 per cent., as this is entirely practi- 
 cable; to require all rivet holes in splices to be reamed with all parts 
 assembled together, or else drilled to a steel template; all holes for 
 connections to be reamed with all parts assembled, or else drilled to 
 steel template. These requirements, of course, are in addition to the 
 standard ones as to rivet spacing, quality of steel, etc. The inspector 
 
23 
 
 at the mill should be required to pay especial attention to these points. 
 If they are properly attended to, the columns can be designed for a 
 minimum stress of 20,000 pounds per square inch, and yet be safer 
 than current practice, based on 16,000 pounds. The execution in the 
 field must also be closely watched by competent inspectors. It is well 
 for the engineer in charge himself to look pretty closely after field 
 rivets and bolts and column bearings. The writer has always done 
 this, and has found it quite necessary. 
 
 In the upper stories of buildings, the ordinary splices will be prac- 
 tically full splices, because of light column loads. In such cases, if 
 the splice rivets are properly put in, it is a matter of minor import- 
 ance for the columns themselves to bear accurately. 
 
 In all construction work, however, it should be borne in mind that 
 execution is often of more importance than design. Good execution 
 will often save a poor design, but no excellence in design can make a 
 structure proof against the evils of poor workmanship. Yet here 
 again the young engineer must remember that there is a practical 
 limit; no work can be done with theoretical accuracy, and it often 
 costs enormously to make a very close approximation. The end in view 
 should be the required factor of safety, attained beyond all doubt, but at 
 the least total expense in dollars and cents. It requires judgment to 
 determine the economical limit between mere labor and mere ma- 
 terial; but it can be said in a general way that current practice in 
 building construction is lavish of material and parsimonious in labor 
 and supervision. Better results could be achieved for less money, by 
 sacrificing part of the material and increasing the standard of work- 
 manship, within reasonable limits. 
 
 Next to the columns, the girders are the most vital members of a 
 steel frame. Little can be added to the chapter on the plate girder 
 in Johnson's Modern Framed Structures. A plate girder for a build- 
 ing should always be designed without stiffeners if possible. Stif- 
 feners form pockets between the flanges, which make the placing of 
 the floor beams very difficult and expensive and add to the pound 
 price of the girder. All things considered, it is usually cheaper to 
 put more metal in the web plate and do away with the stiffeners ex- 
 cept at the ends; here they should never be omitted. All rivet holes 
 in a plate girder should be punched small and then reamed out with 
 all parts assembled. Of course, holes drilled from the solid to a 
 steel template would be ideal; and punched holes are too ragged and 
 match too poorly to be tolerated in first-class work. But the drill- 
 ing from the solid is too expensive in the present state of the art, and 
 the method recommended is probably as good for all practical pur- 
 
24 
 
 poses. Every rivet in a plate girder is supposed to do full duty, so 
 that both the holes and the rivets themselves should be carefully 
 watched. It is in points of this kind that the inspector at the mill 
 should prove his worth; he should never relieve the contractors from 
 responsibility for correct dimensions and fit of various pieces, and, if 
 necessary, should check up no dimensions at all, but devote his whole 
 time to .the quality of the work. 
 
 If rolled beams conform to the usual standard specifications, noth- 
 ing further will be required. Wherever possible, they should transmit 
 their loads to girders and columns through single heavy angle brack- 
 ets without stiffeners beneath, as this avoids introducing tensile stress 
 in the rivets due to deflection of the beam and the concentration of 
 the load on the outer edge of the bracket. The idea is that the out- 
 standing leg of the angle will bend and accommodate itself to the 
 deflection of the beam and thus throw the load close in to the web, 
 where it will produce only shearing stresses in the rivets. 
 
 It is in the details and connections that the structural designer has 
 the best opportunity to show his skill. These make up quite a per- 
 centage of the total weight; they almost never fall below 10 per cent., 
 and often go as high as 20. Cases arise more frequently in buildings 
 than in other structural work, where many heavy connections have to 
 be crowded into a small space. These often demand a great deal of 
 care and ingenuity for their proper solution. 
 
 There are other points affecting the economy of the design in a steel- 
 frame building, however. If columns and girders can be so placed 
 that a girder comes over a partition, it will often be possible to give 
 it the full economical depth; whereas, in another location, the archi- 
 tect might object to so great a projection below the ceiling, and the 
 girder would have to be made shallow, regardless of economy. 
 
 Long spans for beams and girders should always be avoided as far 
 as possible. It is much cheaper to put in more columns, which carry 
 their loads by direct stress, than to use long span deep girders. The 
 span of girder should not exceed 20 feet, unless longer spans are im- 
 peratively demanded. If a bay of the floor system is wider in one di- 
 rection than the other, and the depth of the girders is not seriously 
 limited, it will usually be more economical to run the girders the long 
 way, and the floor beams the short way. 
 
 In making the steel plans for a large building, the columns should 
 first be marked by a system of coordinates, so that the mark of the 
 column would indicate its location. The different stories or tiers 
 would be indicated by prefixing the number of the story or tier to the 
 
25 
 
 mark of the column. Thus if a corner of the building be assumed 
 as an origin of coordinates, the rows of columns in one direction 
 could be lettered, and in the other numbered, beginning in each case at 
 the origin the corner column here being 1-A. The girders can 
 conveniently be designated by the number of the floor and the marks 
 of the columns they connect, while floor beams can receive the number 
 of the floor, the mark of the bay, and their serial number in the bay. 
 By this means, the location of every piece can be determined at once 
 by its marks. The make-up of columns can be conveniently indicated 
 by taking a large sheet and ruling it in parallel vertical columns. 
 Each of these should receive a column mark, and be divided into a 
 number of equal lengths, representing the stories. The make-up of 
 the columns, the location and general character of splices, and levels 
 at which main girders are connected, can all be written and otherwise 
 indicated in the spaces thus laid out. It only remains then to make 
 drawings illustrating typical details and supplement them by proper 
 specifications. 
 
 For the girders, it is best to make a complete drawing for each type, 
 though small variations, covering many slightly different girders, can 
 be indicated on a single type drawing. For floor beams, it is sufficient 
 to indicate their size and weight on the beam plans, and to illustrate 
 their connections by drawings. The beam plan should show column 
 centers by means of crosses or circles, and centers of girders or beams 
 by straight lines. The mark, size, weight, etc., of each girder or 
 beam should be indicated on this plan. 
 
 In writing specifications, it should always be provided, in case of a 
 very large building, that the erector must provide a storage place apart 
 from the building, where the steel can be delivered and sorted, and 
 then brought to the building in the order in which it is-needed for 
 erection. The reason for this is that it is never economical for the 
 mills to turn the material out in this order; there may be girders in 
 all the floors exactly alike; there are sure to be beams that are uniform 
 for all stories; the mills will usually run out all pieces of a kind to- 
 gether. If they were allowed to be delivered at the building, the 
 erection of the lower tiers would soon be stopped by the congestion of 
 materials intended for the upper ones. 
 
 Better prices will usually be obtained if the specifications provide 
 for partial payments on steel delivered at the building, but not fully 
 erected and accepted. To prevent the contractor from taking undue 
 advantage of this, steel delivered at the storage yard and not needed 
 
26 
 
 for immediate erection should not be allowed at the building, nor 
 paid for, until it is brought in, in due course. 
 
 To protect the steel from corrosion during transporation and erec- 
 tion, it should receive a coat of paint or linseed oil before shipment. 
 The best results would be attained by thorough cleansing of the steel 
 in an acid bath or by the sand blast, or both, and the immediate ap- 
 plication of the paint to fresh and perfectly clean surfaces. All trace 
 of acid and of the lubricating oil smeared on during handling and 
 manufacturing should be cleaned off before painting. As a matter of 
 fact, no shop is equipped for treating structural steel in so elaborate 
 a way. It ought to be done, nevertheless, for bridges and viaducts, 
 but it is not necessary for buildings, if proper precautions are ob- 
 served. If the durability of the steel in a building really depended 
 on the paint, the average life of a steel-frame building would hardly 
 exceed twenty-five years. In practice, however, all the steel members 
 are more or less thoroughly covered with Portland cement masonry, 
 and this is the real protection. If it is carried to its logical conclu- 
 sion, so as to secure complete covering and perfect contact through- 
 out, the life of the steel will be indefinite; this will be true, even if 
 the steel is red with rust when built in, provided scales have not be- 
 gun to form. It may stop the corrosion and suspend it indefinitely, 
 even in the latter case. For a discussion of the writer's views on this 
 subject, reference is made to an article published in Engineering 
 News of October 23, 1902, under the title of "Columns for Build- 
 ings." It is sufficient here to say that the corrosion of steel or iron 
 requires the simultaneous presence of an acid, moisture, and oxygen. 
 A limited amount of acid, with an indefinite supply of moisture and 
 oxygen, will ultimately corrode a large amount of steel. Portland 
 cement in contact with steel protects it, because it is alkaline and has 
 a stronger affinity for acids than iron has; it therefore neutralizes any 
 acid before it can attack the steel. Under the conditions existing in 
 buildings, there is enough Portland cement around the steel, if the 
 latter is completely imbedded, to neutralize all the acid that is likely 
 to be absorbed by the covering for hundreds of years. If, however, 
 the masonry is built around the steel, leaving hollow spaces, and if it 
 cracks or has unfilled joints, allowing circulation of the air, the 
 moisture and acid mav reach the steel without being filtered through 
 the masonry, and in that case, corrosion may proceed at a serious 
 rate. For the best results, all the steel should be in close contact 
 with Portland cement mortar over all parts of its surface. 
 
 Closely related to the protection of steel from corrosion is its pro- 
 
27 
 
 tection from fire. The first iron that was used for columns and 
 beams in buildings was introduced with the idea that it would be 
 fireproof. This turned out to be an erroneous idea; but, in modern 
 high buildings there is the additional reason for the use of iron or 
 steel, that, up to the present, at any rate, no other material has been 
 found strong enough to carry the heavy loads without cross-sections 
 so large that the floor space in the lower stories would be seriously 
 diminished. This consideration was what led to carrying the walls 
 of a building as well as the floors on the steel frame. No wall be- 
 ing more than one story high, it was possible to make all of them of 
 a minimum thickness, and reduce them to a mere curtain for keeping 
 out the weather. 
 
 It is vitally important for a high building to be fireproof; all 
 Government structures of any prominence should be fireproof. It is 
 well then to inquire what a fireproof building is, and in what its 
 fireproof character consists. 
 
 A building is entitled to be called fireproof only when it is able to 
 stand an ordinary fierce conflagration without damage, except to 
 paint, plaster, glass, and wooden floor finish, if there is any. This 
 damage repaired, the building must be able to come through a sec- 
 ond indeed many, similar ordeals. Making a building fireproof will 
 not make its contents incombustible, so that quite fierce fires may 
 occur in fireproof buildings; but, although the damage to the con- 
 tents may be 100 per cent., that to the buildings should not exceed 
 5 or 6 per cent., if it is really fireproof. 
 
 To be fireproof, a structure must be incombustible and infusible, 
 and must retain its form and strength unimpaired at any tempera- 
 ture possible in a fire; temperatures in a conflagration rarely exceed 
 2,500 F., although wrought-iron has been known to melt in spots, 
 which would indicate local temperatures as high as 3,000 F. 
 
 Steel and cast-iron are incombustible, but not fireproof. At com- 
 paratively low temperatures they lose their rigidity and are bent and 
 twisted in every conceivable way. When this happens, the floors are 
 destroyed, the contents of the building are precipitated to the ground, 
 the expansion of the steel often throws the walls, and the wreck is 
 worse than if the floors and columns had been entirely of timber. 
 
 The fireproof problem generally consists in devising a covering for 
 steel and iron which will protect the steel from high temperatures, 
 resist the fire itself, and have sufficient strength to resist ordinary 
 wear and tear. This covering is nearly always some form of masonry. 
 
 Very few natural stones can resist high temperatures. Limestones 
 
28 
 
 and marbles are destroyed by driving off the C O 2 ; all stones crack 
 and fly to pieces, except some rare forms of sandstone, when exposed 
 to high temperatures. While stones are incombustible they are not 
 fireproof. 
 
 The various forms of burned clay all have more or less power to re- 
 sist heat. They have all been subjected to fairly high temperatures 
 in burning, and they are all relatively poor conductors of heat, which 
 is essential if the steel is to be prevented from attaining a high tem- 
 perature. Dense, hard burned clay, however, when subjected to the 
 sudden changes of temperature, is very liable to crack, although it 
 does not fly to pieces as stone does. In the kiln it is subjected to 
 very great changes of temperature, but they are very gradual. When 
 used for fireproofing, clay products are generally known as terra cotta. 
 By this name they will be called hereafter. The clay used for terra 
 cotta fireproofing should be strong and tough, and should not melt at 
 temperatures less than 3,000 F. It should be thoroughly burned, and 
 should require a temperature of at least 2,300 to 2,500 F. to accom- 
 plish this. It is much more efficient both as a non-conductor and in 
 resisting strains due to sudden changes of temperature if as large a 
 proportion of sawdust as possible is mixed with it before burning. 
 This produces what is known as porous terra cotta. If burned hard 
 enough for the highest efficiency, it can not be cut with a saw and 
 will not hold nails, as is often claimed for it. Even the softer grades 
 commonly used can not be depended upon in this respect, the state- 
 ments in the maker's catalogues to the contrary notwithstanding. 
 Selected pieces can always be found of which it is true, but no large 
 deliveries will contain a sufficient percentage of such pieces to be 
 depended upon. 
 
 No fireproof material is superior to the best grades of porous terra 
 cotta, when it is properly applied. In the form of the hollow blocks 
 ordinarily found -in the market, however, it is merely fire-resisting, not 
 fireproof. These blocks have very thin webs; when exposed to the 
 fire, they very quickly become heated through. They are backed by 
 dead air spaces, and are joined at the corners of the blocks to other 
 thin webs not exposed to the fire. The result is very serious strains 
 due to unequal heating of the block as a whole, with comparatively 
 sudden transition from the hot to the cold parts. This alone will 
 cause the outer webs to crack and fall off in a hot fire, and the appli- 
 cation of cold water from a fire hose brings this about at once. The 
 hollow tiles were developed with a view to lightness, and with the 
 idea that the dead air spaces would increase the protection from fire. 
 
29 
 
 The latter is a fallacy; the effects of unequal distribution of heat 
 were not foreseen and do not seem to be fully realized yet. Two 
 fires in a store building, known as the Home Store, in Pittsburg, in 
 the years 1897 and 1900, illustrated this weakness of hollow tile very 
 well. These fires will be found described in the Engineering Record 
 of May 22, June 26, and July 17, 1897, and of April 14, 1900. Hollow 
 tiles present two or more parallel webs of thin section, separated by 
 dead air space, when in place. To expect those to successfully resist 
 a fierce fire, is like holding a military position with a series of thin 
 skirmish lines, the most advanced of which occupies the key to the 
 whole position. When it is known beforehand what the exact loca- 
 tion of the supreme trial of strength is to be, it follows that there 
 should be concentrated the full strength of the defense. This is as 
 true of fireproofing as of a battle. When the outer webs are broken 
 off, the hollow blocks themselves are a total loss, even though they 
 may still protect the steel with more or less success. What is true in 
 this respect of porous terra cotta is doubly true of the dense variety. 
 
 To make hollow blocks really fireproof, the webs should be 2 inches 
 thick. The material can not be successfully and economically burned 
 in greater thickness than this, or it would be desirable to make it 
 greater. 
 
 A better form of fireproofing would be 4 inches of brickwork, in 
 which the bricks were made solid of porous terra cotta. But where 
 flat ceilings are required, flat floor arches of hollow blocks, with webs 
 2 inches thick, can be safely used. They will not be found in stock, 
 but must be made to order. The reason the thicker webs, or the 
 solid bricks, are more successful in resisting fire is that there is a 
 greater thickness of homogeneous material, and the change of tem- 
 perature from hot to cold is gradual. The resulting strains do not 
 exceed the strength of the material at any point. Of course, the 
 thicker webs make heavier blocks, and this requires more steel to carry 
 the dead load. Herein lies one reason for the continued use of 
 blocks too light to be efficient for fireproofing. Another is the in- 
 creased cost of the heavier blocks themselves. 
 
 Flat floor arches are almost always made with parallel joints, from 
 motives of economy in manufacture; it reduces the number of sepa- 
 rate patterns required and makes it easier to allow for accidental varia- 
 tions in the spacing of floor beams. While parallel joints seem all 
 wrong, from a theoretical point of view, in practice they are all 
 right. Flat side construction hollow tile arches almost invariably 
 fail bv shearing the webs of the blocks nearest the beams i. e., in 
 
30 
 
 the skewbacks; so the joints are stronger than the blocks. End con- 
 struction arches, with thin webs, are very difficult to set properly, be- 
 cause of the small area of end section available for receiving the 
 mortar. In these blocks the joints may be the weakest part and 
 should be carefully looked after. If webs were made 2 inches thick^ 
 this trouble would be largely obviated. Conditions would be still 
 further improved by inserting thin continuous slabs in the joints, but 
 this is never done, except to make up for accidental variations in the 
 spacing of beams. 
 
 No matter what kind of floor arch is used, the lower flanges of the 
 beams should be protected with at least 2 inches of fireproof material. 
 The best method of doing this, probably, is with a heavy protecting 
 skewback of the same material as the arches. Metal laths and plaster 
 will not do; the fire will strip them off in ten or twelve minutes, and 
 if the fire does not the water will. In the case of a protecting skew- 
 back, the design must be such that the pressure of the arch, under its 
 load, will not tend to break off the protecting flange. This will have 
 quite enough to do if it stays in place under the action of fire and 
 water. 
 
 For the protection of girders, heavy shoes should be made in two 
 pieces to fit over the lower flange ; even at some extra expense, the th ick- 
 ness of the material in these shoes should be made at least 2% inches. 
 The shoe should be filled with Portland cement mortar and squeezed 
 into place; as soon as the cement is sufficiently set, the web covering 
 should be built up on either side. The best form of this is 4 inches 
 of porous terra cotta brickwork. It is somewhat heavy, of course, 
 but when completed it possesses considerable transverse strength, 
 and will transmit a part of its own weight to the columns. Instead 
 of 4 inches of solid brickwork, the side covering might be built of 
 hollow blocks with webs at least 2 inches thick; but the weight 
 would be the same, and the solid brickwork is more efficient. 
 
 Columns should always be covered with 4 inches of solid brickwork 
 and all interior spaces filled with Portland cement concrete. It has 
 been repeatedly demonstrated that 4 inches of brickwork will protect 
 steel in any ordinary conflagration, and if it is sufficiently tough and 
 refractory itself it will be good for many fires, instead of only one. 
 Porous terra cotta should be used because it is a poor conductor, and 
 is able to take up contraction and expansion within itself without 
 developing cracks. It should be hard burned to enable it to stand 
 mechanical shocks, to which it is sure to be subjected in practice, 
 and it should be highly refractory to prevent it from melting. It 
 
31 
 
 would be well to specify that porous terra cotta for fireproofing should 
 be made of tough, refractory clay, with at least 20 per cent, of its 
 volume of sawdust mixed with it before molding. That it should be 
 burned almost to vitrification, and must be able to stand a temperature 
 of at least 2,800 F. without melting or running. These specifica- 
 tions can be complied with at a small extra cost as compared with the 
 materials commonly used. The extra cost should not exceed one-sixth. 
 The result in the work will be better by 100 per cent. The same 
 grade of materials should be used for floor arches, and for column and 
 girder coverings. If flat ceilings are not required, a segmental arch 
 of the solid porous terra cotta bricks, with heavy protecting skewbacks, 
 can not be excelled. To secure a flat ceiling with these floor arches 
 would require metal lathing to be stretched under them, at an extra 
 cost of 5 or 6 cents per square foot of floor. The floor arches them- 
 selves ought not to cost more than 25 cents to 27 cents per square foot of 
 floor. In considering the relative importance of different parts of the 
 fireproofing, it should be remembered that the failure of a single floor 
 arch or floor beam is a comparatively small matter; the failure of a 
 girder is more serious, and that of a column is a catastrophe. Accord- 
 ingly, the column protection should be the first, the girder covering 
 next, and the floor system last, in power of resistance, if there is any 
 difference. In current practice, this order is just reversed; in the forms 
 recommended herein, it is realized. The column and girder coverings 
 recommended will cost at least twice as much as those in common 
 use, but the expenditure is fully justified by the results. 
 
 In the case of the columns, they will be so greatly stiffened by the 
 covering and concrete filling that they can be safely designed without 
 reference to buckling in simple compression. This will enable 
 enough steel to be saved to more than pay for the extra cost of the 
 covering, and the completed column will be both cheaper and better 
 than those used in current practice, with their flimsy hollow tile 
 covering. 
 
 Next to porous terra cotta, concrete is the best material for fireproof 
 purposes. When made with Portland cement, it will withstand very 
 high temperatures without material injury. The best concrete for 
 resisting fire is made of Portland cement, sand, and the ash and clinker 
 from steam boilers in large power plants. Domestic ashes and ashes 
 from small plants are apt to contain a good deal of unburned coal, 
 which always has sulphur in it; this is liable to corrode the steel. 
 Where the coal is entirely burned, however, practically all of the sul- 
 phur goes off with the volatile products of combustion, and the ashes 
 
32 
 
 left behind will not corrode iron. Cinders, like locomotive cinders, 
 which consist practically of bits of coke, are combustible and corrosive ; 
 they never give a good bond with cement, sd they make a very weak 
 concrete. They should never be used. There are cases on record 
 where concrete made of them has been subjected to the heat of a fire, 
 and has slowly burned up. 
 
 Concrete, made with broken stone, when subjected to heat, cracks 
 and flakes off to some extent, just as the stone itself does. Gravel 
 concrete stands heat better, and seems to give greater strength when 
 reinforced with steel bars than stone under like conditions. Broken 
 brick gives a concrete stronger than that obtainable from ashes and 
 clinker, and probably stands fire just as well. Furnace slag is said to 
 give a good fireproof concrete when broken and used in the same way 
 as gravel or broken stone. There is likely to be some sulphur in 
 furnace slag in a dangerous form, especially if the slag is finely 
 divided. If slag is to be used, it would be well to screen out all 
 crusher dust and wash the slag, so as to have all pieces clean and not 
 smaller than a pea. Under these conditions, the sulphur is not likely 
 to be very active. Portland cement clinker and neat Portland cement 
 made into concrete, make a product that can not be excelled for fire- 
 resisting properties. Many cement mills mold their kiln linings from 
 such a mixture, and find it superior to the best fire bricks. This ma- 
 terial, however, is not generally available for fireproof work. Port- 
 land cement is burned at temperatures probably as high as 3,500 to 
 4,000 F., so the clinker has passed through a more than ordinary 
 severe test in the process of manufacture. The only weak point 
 about Portland cement concrete is the fact that water has been added 
 to it and taken up in the process of setting. This water can prob- 
 ably be driven off, in large part at least, by the application of heat. 
 But it is possible that the cement is to some extent re-clinkered by 
 this; if so, the concrete ought not to suffer serious diminution of 
 strength. Practical tests show that, as a matter of fact, it does not; 
 whether this is due to re-clinkering, is another question. A fierce 
 fire will probably damage stone or gravel concrete, and possibly brick 
 and cinder concretes, to a depth of about three-fourths of an inch, so 
 that the damaged layer will either come off or have to be taken off. 
 It would be well, in using concrete for fireproofing, to add about an 
 inch extra thickness all around; then, in the event of a fire, the 
 damaged concrete could be cleaned off and its place supplied by metal 
 lath well fastened on and plastered with Portland cement mortar. 
 
33 
 
 This would probably prevent the damage in a second fire from pro- 
 ceeding farther than that due to the first. 
 
 In using concrete for fire protection, the minimum thickness should 
 be about the same as for terra cotta, and all column and girder cover- 
 ings should have a skeleton of light metal shapes to hold them to- 
 gether and give them tensile strength. 
 
 Within recent years concrete, reinforced with steel bars, has been 
 much used under transverse stress. It is used in flat slabs between I 
 beams, instead of floor arches. In some cases, it is used as an arch 
 proper, built on a wire lath center; but in this case it is considered 
 as an arch, pure and simple. The metal is not counted on to fur- 
 nish any part of its strength. But beams, girders, and columns are 
 also built now of reinforced concrete with entire success. Frames 
 of buildings have been built of it in Europe, similar to the steel 
 frames used here, only on a smaller scale. It seems destined to play a 
 most important part in the structural work of the future. It would not 
 be surprising if it should ultimately drive out steel-frame construction 
 altogether. Where it can be suitably used it probably yields, con- 
 sidering its cost, a greater return in the way of durability, strength, 
 and fireproof qualities combined than any other form of construction. 
 It is designed on the assumption that the concrete in the upper part 
 of a beam, girder, or floor plate takes all the compressive stress, while 
 the tensile stress in the lower part is taken entirely by the steel rein- 
 forcement, or partly by the steel and partly by the concrete. A great 
 many formulae have been worked out for the design of reinforced 
 concrete beams under flexure. They are all based on the ordinary 
 theory of flexure, modified to suit the circumstances and the indi- 
 vidual views of the author. Probably as convenient a set of working 
 formulae as any can be found in the latest catalogue of the St. Louis 
 Expanded Metal Company, which contains a discussion of the subject 
 by Mr. A. L. Johnson, Member American Society of Civil Engineers. 
 It is probable that his formulae are as reliable as any others available at 
 the present time. It should be stated, however, that the writer has 
 not been able, so far, to verify equation 23, on page 58, and of course 
 this applies to all the subsequent equations depending upon it. Only a 
 very little time has been spent upon equation 23, and it is quite pos- 
 sible that it is correct. Another equation in this catalogue that 
 seems to be wrong is No. 39, page 62. The writer thinks this 
 
 i_ i j i_ o ic cos v/ sin *J 
 
 should be o = 
 
 2 
 
 A word might be said here as to the value of catalogues as sources 
 
34 
 
 of professional information. Along with the technical periodicals, 
 and transactions of the Engineering Societies, they constitute the 
 most valuable and indispensable part of an engineer's library. A 
 treatise, setting forth the fundamental principles of any branch of 
 engineering, is useful as the first step. But so far as the details of 
 practice go, it is out of date before it is printed, and the engineer 
 who wishes to be abreast of the times must derive his information 
 from current literature and the practice of leading contractors and 
 manufacturers. It should be remembered that, more and more, 
 contracting work and industrial processes are passing into the con- 
 trol of trained engineers. These engineers supply the information 
 that goes into the catalogues. They are generally honest men and 
 state what they really think; they would not dare to make seriously 
 inaccurate statements of a technical nature; they are in a better 
 position than any other men to get accurate knowledge ot the details 
 of their specialties; and, as a matter of fact, on many branches of 
 engineering, the catalogues of certain large concerns are the best 
 and most reliable source of information. The fact that it is coupled 
 with advertising matter should not be allowed to belittle the value of 
 the information they contain. 
 
 Probably the best work on reinforced concrete is "Beton Arme, '* 
 by M. Christophe. No thoroughly satisfactory work is printed in 
 English, but a series of articles descriptive of the experiments of 
 M. Considere on hooped concrete has been published in recent numbers 
 of the Engineering Record, and should be read by every one interested 
 in the design of reinforced concrete columns. 
 
 In addition to terra cotta and concrete, plaster of paris has been 
 extensively used for fireproofing. But this substance rapidly deterio- 
 rates under fire and water, is mechanically frail, and should not be 
 used, as a general thing, in important buildings. There are circum- 
 stances under which it is suitable, but there is not space to go into 
 this subject here. The writer would have been glad, indeed, to go 
 more extensively into the whole subject of fireproof construction, for 
 in no other part of a building is there more need of an engineer's 
 special training and in none is the lack of the engineer's work more 
 glaringly apparent; but the limitations of time and space prevent a 
 full discussion, and other points must be touched upon. 
 
 HEATING AND VENTILATION 
 
 Most modern buildings are heated, in some way, by either steam 
 or hot water. If radiators are placed in the rooms to be heated, the 
 
35 
 
 system is called direct; if they are placed in the basement and used 
 to heat air which is forced over them and through hot-air flues into 
 the rooms, the system is called indirect. If the radiators are placed 
 under windows, with provision for the admission of fresh air over 
 their heated surfaces through openings under the window sills, the 
 system is known as the direct-indirect. In any of these systems, 
 either steam or hot water may be used. If a blower is used to insure 
 the movement of air over indirect radiation, it is called a plenun sys- 
 tem; if an exhaust fan is used it is a vacuum system. The latter is 
 almost never used in indirect heating, however, as it is not as reliable 
 as the other. All the necessary details and calculations for a steam- 
 heating plant can be found in "Baldwin on Heating," and in a book 
 on the same subject by Prof. R. C. Carpenter. "Hot Water Heating 
 and Fitting" is the title of another work by Baldwin, which is a 
 standard on the subject. 
 
 A steam-heating system consists of a boiler to evaporate the water, 
 supply pipes forcarrying the steam to the radiators, radiators forcondens- 
 ing and making available its latent heat, and return pipes forcarrying 
 the condensation back to the boiler. The supply and return pipes are 
 sometimes combined in one set, giving a "one pipe" system. This 
 is suitable only for small plants. In all such cases, the condensed 
 water falls back through the rising steam, and the pipes must be made 
 large enough to permit- of this without interfering with the necessary 
 supply of steam. In the case of steam heaters, a damper regulator, 
 consisting of a diaphragm, weighted on one side, and subjected to 
 the steam pressure on the other, can be very advantageously used for 
 automatic regulation. As the steam pressure rises above a certain 
 point, it raises the arm carrying the weight, and by means of a chain 
 connection closes, or partly closes, the damper supplying air to the 
 fire or regulating the draft. By shifting the weight the pressure in 
 the system may be changed from day to day, according to the temper- 
 ature. For small plants, this is a great convenience, "and enables the 
 plant to get along quite satisfactorily with only occasional attention. 
 No other system of heating admits of automatic regulation in 50 
 simple and direct a way. 
 
 In tall buildings it is customary to take the main supply pipe 
 direct to the top of the building, and then distribute downwards. 
 This gives much more positive results, and may be said now to be 
 the general practice. Ordinarily, where low pressure steam is used, 
 some sort of air valve is put on the radiators to enable them to expel 
 the air; otherwise the radiators will remain cold, as the steam will 
 
36 
 
 be unable to fill them. Air valves generally act -by the unequal 
 expansion of two metals. Many of them are quite reliable, if properly 
 placed on the radiators. 
 
 In large installations, however, it is often the case that a vacuum 
 pump is placed on the returns. This speedily empties the entire 
 system of air, and increases the effective pressure of the steam by 
 creating a vacuum in front of it. The supply pipes can be made 
 much smaller than where the steam and condensation are expected to 
 circulate under gravity and low pressure alone. Up to the present, 
 no book on the subject has treated this phase of the subject with 
 thoroughness, and information concerning it can be obtained only 
 through the current publications, and from people controlling certain 
 patents in reference to it. Steam has the advantage in climates sub- 
 ject to sudden changes, that heat can be obtained quickly, and gotten 
 rid of quickly, since the weight of water required to fill the system 
 with steam is comparatively small. 
 
 A hot-water plant includes a heater, supply and return marns, 
 radiators, and expansion tank at the highest point of the entire 
 system. All the pipes, radiators, tanks, heaters, etc., are filled with 
 water. This entire volume has to be heated before its effects are felt 
 in the rooms, and must cool off again before the rooms will cool. 
 It gives a very equable and satisfactory temperature, but is more suit- 
 able for rigorous climates than comparatively mild ones. Great care 
 is required in laying out a hot-water plant to insure efficient circu- 
 lation. 
 
 In a general way, indirect hot water is the most expensive system, 
 indirect steam next, then direct hot water, and finally direct steam. 
 
 Open fires and hot-air furnaces are still often used in private houses. 
 Both are satisfactory under certain conditions, but neither can be 
 recommended for general application. 
 
 PLUMBING 
 
 The object of the plumbing in a house or building is to supply 
 water and gas at the necessary points, and to carry off all liquid and 
 solid waste, into the sewers or other systems of disposal. Piping a 
 house for gas and water is comparatively simple. The other matters 
 are more complicated. The various fixtures connected with the 
 drains comprise water closets, baths, lavatories, kitchen and pantry 
 sinks, urinals, laundry tubs, and slop sinks. These must all be con- 
 nected by suitable pipes with the drains and sewers. The drains in 
 
37 
 
 the house are known, in a general way, as soil pipes. All sewers are 
 filled with offensive gases; it has been very generally believed that 
 these gases were a source of disease; while this danger is probably 
 exaggerated, sewer gas is a most unpleasant constituent of the air in 
 a dwelling house. Even the soil pipe in a house becomes foul enough 
 to be a source of disagreeable odors; drains leading from wash basins, 
 baths, sinks, and tubs, become coated with a slimy, ill-smelling; de- 
 posit on the inside. An ideal system of plumbing provides for cut- 
 ting off the house from all these sources of bad odors, just as near the 
 various fixtures as possible. The means used is always a trap in the 
 drain itself, so arranged as to provide a water seal between the house 
 and the drains. All parts of the waste pipe between the traps and 
 the house should be accessible for inspection and cleaning. It is also 
 found necessary to provide for a free circulation of air through the 
 soil pipes to secure the best results, and to prevent a discharge of 
 water from a fixture above, from syphoning off the water in a trap be- 
 low, thus leaving the house open to the drains. As the house is 
 usually warmer than the ground, especially in the winter, there is 
 nearly always an inward draft, tending to draw air from sewers into 
 the house. 
 
 Two prints* are attached hereto, showing two ways of piping a 
 house. In one, a connection is made -from the sewer side of every 
 trap to the open air, above all fixtures, with the idea of securing cir- 
 culation and a supply of air to restore the pressure when a discharge 
 passes through the adjacent soil pipe, thus preventing the water seal 
 in the trap from breaking. In the other, these "back-air vents," as 
 they are called, are omitted, but the ends of all wastes are carried to 
 the open air above all fixtures. This is just as good and somewhat 
 simpler than the other plan, although it takes more pipe. This lat- 
 ter system provides for an exceedingly thorough circulation in all the 
 drain pipes. There are some persons who object to the fresh-air 
 inlet in front of the house, as it sometimes emits foul odors from the 
 house drains. But, on the whole, it seems better to retain it, as the 
 amount of fouling in the house pipes is not very great, and the draft 
 will generally be in at the fresh-air jnlet and out through the pipe at 
 the top of the house. If any opening is made on the sewer side of 
 the house trap, it must always be carried above the roof. All traps 
 should have means of getting at them to clean them out without 
 breaking the drains. This is indicated by the letters C. O. on the 
 drawings. All clean-out openings must be stopped gas tight and 
 water tight with a plug, and opened up only when the trap needs at- 
 
 *Not printed. 
 
38 
 
 tention. For soil pipe, cast-iron and steel are used. Cast-iron 
 soil pipe comes in lengths of 5 feet, with hubs and spigots for calk- 
 ing. There are two weights, standard and extra heavy; the latter 
 should always be used. The pipes should be dipped, hot, into melted 
 asphalt or coal tar, so as to give them a thorough coating, both in- 
 side and out. Fittings for cast-iron soil pipe should all be of the 
 long turn or. sanitary kind, to reduce friction and prevent deposits. 
 Steel pipe, for waste purposes, should be extra heavy, and used with 
 the special recessed drainage fittings to be found in the catalogues of 
 the best makers. These recessed fittings have shoulders inside against 
 which the pipe abuts. The shoulder is of the same thickness as the 
 pipe and insures a continuous smooth surface on the inside. Where 
 steel pipe and screwed fittings are used, flanged joints should be in- 
 troduced at convenient points, so that if repairs or changes necessitate 
 breaking the line of pipe, it can be done with a minimum of damage 
 and expense. Steel drainage pipes are sometimes galvanized; this is 
 good for the outside of the pipe, but of doubtful value on the inside; 
 decomposing animal matter gives rise to acids, and if the inside of the 
 pipe is galvanized there will be galvanic action, which will be quite 
 deleterious, and hasten the destruction of the pipe. There is no 
 reason why steel drainage pipes should not be dipped in hot asphalt; 
 the result would be better. 
 
 After the question of pipes is settled, there remains the fixtures and 
 traps. The ideal plumbing fixture is made of vitreous ware, practi- 
 cally like porcelain. It has a hard surface glaze, but is vitreous all 
 the way through, so that if the glaze is cracked, it will not absorb 
 any unclean fluids. It is free of crazing i. e., cracking of the glaze, 
 and is made as nearly as possible in one piece, without joints or other 
 places where dirt can collect. There are only two concerns in the 
 United States making thoroughly first-class plumbing material. One 
 of these is the J. L. Mott Iron Works, and the other is the Meyers- 
 Sniffen Co., both of New York. There are a number of large job- 
 bing houses that handle plumbing materials and fixtures, but they 
 handle many grades besides the best. The Mott Works make some 
 cheaper goods for which there 'is a deman'd, but they can be trusted 
 not to sell them for anything except what they are. The jobbers 
 may be perfectly reliable in matters of this kind, but some of them 
 are not. It is understood the Meyers-Sniffen Co. does not handle 
 any of the cheaper grades of plumbing materials at all. 
 
 Some fixtures, such as bath tubs, very heavy water closets, slop 
 sinks, pantry sinks, etc., have to be made so thick that they can not 
 
39 
 
 be made of the vitreous ware, which can be burned only in thin 
 pieces. The heavier sections are made with a fire clay body and a 
 hard glaze. The maker should guarantee them against crazing, and 
 the fire clay body should be almost vitrified. 
 
 The only way to test the quality of porcelain fixtures is to break 
 them across and test them for strength and absorption. Vitreous 
 ware, or, as the Mott catalogues call it, vitro-adamant, should be ab- 
 solutely non-absorbent all the way through. The fire clay wares will 
 absorb a certain amount of water; but they should be burned so 
 hard that if hydrostatic pressure be introduced into the pores, the 
 ware will not crumble to pieces under less than 1,500 pounds per 
 square inch, or more. It is possible to form a very fair idea of the 
 degree to which fire clay has been burned by simply testing its hard- 
 ness. The same is true, to a limited extent, of the vitreous ware. 
 
 Any plumbing fixture, in addition to being made of thoroughly 
 sanitary, non-absorbent material, must be of a proper shape and size. 
 This can best be illustrated by considering the case of the water 
 closet. This fixture, in its early form, consisted of a porcelain or 
 porcelain lined bowl, with a movable pan for a bottom. When the 
 closet was used, a handle was pulled, which dumped the pan, flushed 
 the bowl, and filled the pan again with water. The pan was dumped 
 into a sort of hopper which communicated with the soil pipe through 
 a trap. The sides of the hopper formed a large inaccessible surface, 
 which soon became very foul. An improvement in this consisted in 
 the use of a bowl emptying into a trap through an opening closed by 
 a plunger valve. The bowl had a flushing rim and could be kept fairly 
 clean, but there was much fouling space around the plunger. Then 
 came a porcelain bowl or hopper, with a flushing rim, supplied from 
 a tank. This was the first really successful solution; but the surface 
 of water presented for the reception of excrement was small, and the 
 sides of the bowl became soiled and required much attention. An 
 attempt to remedy this led to the form known as the washout closet, 
 which was really a step backwards. Then the hopper and trap were 
 combined in one piece of porcelain, and efforts made to enlarge the 
 water surface. It was found impracticable to make this ferm flush 
 properly with a large water surface; moreover, it would not flush 
 successfully with a very deep seal in the trap. Not over an inch seal 
 was used at first. By dint of much experimenting, forms of the 
 simple combined hopper and trap have been developed which present 
 a reasonably large water surface, have a seal of nearly 2 inches, and 
 flush very successfully. For use in public places these are to-day the 
 
40 
 
 most desirable forms. But a modification, known as the syphon jet 
 closet, is better for private houses. In this form a part of the flush 
 is directed through a jet arm, which discharges at the bottom of the 
 trap upwards and towards the soil pipe. This enables a very large 
 body of water to be maintained in the bowl, with a very deep seal 
 as much as 3 inches, in some cases. The jet moves the entire 
 volume of water along, together. As soon as it begins to pass through 
 the outlet a vacuum is created, and the contents of the bowl are 
 ejected by syphonic action with a rush. The bowl then refills from 
 the flush. The outlets of all syphonic closets have a rather tortuous 
 form; this is to retard the water enough to form a partial vacuum 
 in the outlet itself. It has been found possible in the case of a wash- 
 down closet which is another name for the combined hopper and 
 trap to secure some syphonic action by enlarging the outlet and then 
 contracting it again, and also by making it more or less tortuous. This 
 has made a deeper seal possible, which is a matter of great importance. 
 The limits of time and space prevent further discussion of plumb- 
 ing fixtures and many other points that require attention in buildings, 
 but it is hoped that the fragmentary notes contained herein may prove 
 of some value and smooth out a few of the difficulties that present 
 themselves to a young engineer engaged for the first time in the 
 erection of a building.