A 
 
 Al 
 
 = 
 
 
 ^ 
 
 ^^S 33 
 
 i 
 
 ^^S 33 
 
 4 = 
 
 GION 
 
 1 
 
 6 = 
 
 == r — 
 
 4 = 
 
 
 
 3) 
 
 1 = 
 
 ==^ 33 
 
 7 ^ 
 
 :^=^= -n 
 
 
 
 7 ^ 
 
 
 
 
 = 
 
 
 5 
 
 U.S. Architect of Public Biiildings 
 Report 
 1651/52
 
 THE LIBRARY 
 
 OF 
 
 THE UNIVERSITY 
 
 OF CALIFORNIA 
 
 LOS ANGELES 
 
 aBONia laiHdwvd
 
 if'' 
 
 ■^
 
 REPORT 
 
 OF THE 
 
 ARCHITECT OF PUBLIC BUILDINGS, 
 
 ACCOMPANYING 
 
 THE PRESIDENT'S MESSAGE 
 
 AT THE 
 
 SECOND SESSION OF THE THIRTY-SECOND, CONGRESS. 
 
 WASiriNCiTON: 
 ROBERT ARMSTRONG, PRINTER.
 
 UBL 
 
 REPORT OF THE ARCHITECT OF PUBLIC BUILDIXGS. 
 
 Architect's Office, United States Capitol, 
 
 Washington, D. C, December 1, 1852. 
 
 Sir : In conformit}'' to a resolution of the Senate of the United 
 States, passed August 26, 1852, I have the honor to lay before you the 
 i'oUowing "nbstract or compendium" of my annual report, which is 
 herewith submitted : 
 
 Extension of the Capitol. 
 
 The appropriation for continuing the w-ork not having been made 
 until the 3 4th of April last, the buildings are not as far advanced as I 
 inticipated at the date of my last annual report. The contracts all 
 being limited to existing appropriations, the contractors were not at 
 liberty to make preparations for supplying materials until after the 
 passage of the bill. 
 
 As soon as the appro])riation was made, the contractors promptly 
 commenced operations, and the work has since been prosecuted as 
 rapidly as a proper regard for its permanency, durability, and beauty 
 would warrant. 
 
 The cellars of both wings are completed, the arches to support the 
 basement floors ai'e finished, and the outside marble work is })rogrcss- 
 ing raj)idly. 
 
 All the foundations are permanently laid on the natural, undisturbed 
 earth ; some of them are 40 f^'t deep, and none less than 15 feet 
 below the ground line of the building.* The character of the earth un- 
 der all the walls is the sameythroughout, being a stratum of compact 
 gravel of several feet in tliickness* The walls are all built widi great 
 care, and the entire sub-structure is massive and solid;* The stones of 
 which these foundations are constructed were tested, at the recjuest of 
 a speci;il committee ol" th<! House of Kepresentativcs, by the late Pro- 
 fessor Walter 11. Johnson, whose report is hereto appended. 
 
 The rnarblc for the exterior has been delivered as rapidly as we 
 have re(|iiirfd it ; twenfy e;irgoes have arrived since the 5tli of July 
 last, containing, in the aggregMle, ;J5,2'J(> cubic fix-t, bciug an average 
 of 1,487 cubic li^et per week. Jiefore this marble was adoj)led, it was 
 tested by a commission ap[)ointed for the purpose, and their report is 
 hereto annexed. 
 
 in coriformitv to the proviso contained in the first section f>f the art 
 of Congress approved August iJl, 1852, I appoint(ul Mr. John C. 
 Harkness as measurer of all the work and materials of the ext(Mision 
 of the Ca[)itf)l, and Mr. Cornelius .Jiieobs receiver of materials f()r the 
 north wing, and Mr. Willi;ini J. Smith on the south wing; all of whoui 
 were duly sworn into oiliee. 
 
 All the work done, and materials fnrnished by contract, have since 
 been measured by Mr. Harkness, and no further payments were madev 
 until the measurement was reported to this office, in conformity to tb«- 
 aforesaid act of Congress.
 
 4 
 
 Tlio whdlc amount nppropriatod, thus far, for the exten- 
 sion of the Cai)itol is $000,000 00 
 
 And tlio total amount cxpondt-d to this date (December 1, 
 
 185:2) is 495,799 97 
 
 Leaving an unexpended balance of. 104,200 03 
 
 There \vill be recjuired to carry on the work during the 
 })resent fiscal vear, ending June 30, 1S53, the addi- 
 tional sum of. '. $400,000 00 
 
 And during the ensuing fiscal j'ear, ending June 30, 1S54, 600,000 00 
 
 Making 1,000,000 00 
 
 Library of Congress. 
 
 On the 27th of January last I submitted designs for reconstructing 
 the main library room, with arrangements for future extension, which 
 were adopted, and on the 19th of March an appropriation of $72,500 
 was made to carry out the plans. Tlie work was immediately com- 
 menced, and every possible exertion has been made to complete it 
 before the assembling of Congress ; it will, however, be ouf of our 
 power to finish it entirely for several weeks to come, notwithstanding 
 the workmen have been constantly and cn(Tgetically employed, night 
 and day. The entire room is fitted up with iron, and the ceiling is 
 composed of the same material, so that nothing combustible enters in 
 any way into its construction. 
 
 The damage done by the fire to the western front has all been re- 
 paired. 
 
 The hot water furnaces, for warming the library and the adjacent 
 rooms are completed and in operation. 
 
 The appropriation made for " the repairs .jf the Congres- 
 sional Library,'' by the act of Congress a})proved 
 March 19, 1S52, amounted to $72,500 00 
 
 Of which there have been exj)cnded to the present date 
 
 (December 1, 1S52) 51,703 24 
 
 Leaving an unexpended balance of. 20,790 76 
 
 The Patent Office Buildings. 
 
 The interior of the eastern wing is nearly completed ; the basement 
 and principal stories are now ready for occupancy. The hot water 
 furnaces are completed and ready to be put in oj)eration. The eastern 
 portico is far advanced to completion, and may be finished in a few 
 weeks. 
 
 The work has been resumed on the western wing, and the granite 
 sub-basement is now being constructed. 
 
 THOMAS U. WALTER, 
 
 Architect of FuOlic Buildings. 
 Hon. Alex. H. H. Stuart, 
 
 Secretary of the Interior.
 
 Architect's Office, United States Capitol, 
 
 Washington, D. C, December 1, 1S52. 
 
 Sir : I have the honor to lay before you the following report of the 
 state of the public works under my charge, and their progress during 
 the past year ; 
 
 Extension of the Capitol. 
 
 The appropriation for continuing the work on the Capitol not having 
 been made until the 14th of April last, the buildings are not in the state 
 of forwardness I anticipated at the date of my last annual report. The 
 contractors for furnishing materials were not at liberty, during the pen- 
 dency of the bill, to make any arrangements for prosecuting the work, 
 as the contracts all contain an express stipulation that " in case Congress 
 should, at any time, ffiil to make the appropriations necessary to carry 
 on the work, the said contracts shall be suspended, without thereby 
 creating any claim on the United States." 
 
 No preparations were, therefore, made for quarrying building- stone 
 for the foundations, granite for the sub-basement, or marble for the su- 
 perstructure, until after the passage of the bill, so that we can scarcely 
 be said to have been in full operation until the middle of the season. 
 
 Immediately after Congress had made the appropriation, the contract- 
 ors promptly commenced the execution of their several contracts, and 
 the most energetic means were used throughout the remainder of the 
 season to accelerate the work as rapidly as was consistent with a 
 proper execution of its several parts, and a due regard for its perma- 
 nency, durability, and beauty. 
 
 The cellar walls of both wings are completed, tlic arches to support 
 the floors of the basement story are finished, and the outside marble 
 work is progressing rapidly and satisfactorily ; the setting of the marble 
 has been commenced, and the walls are raised, in some places, to the 
 height of twelve feet above the granite sub-basement. 
 
 Provision is made throughout the entire sub-structure for the system 
 of warming the buildings, described in my last annual report, and all 
 the necessary flues are commenced in accordance tlicrewith. 
 
 All the foundations have permanent footings on the natural, undis- 
 turbed earth; ni;my of tlicm are laid at the depth of ^/V;/ tl-ct, and 
 none of tln;rii less \.\v,n\ fifteen feet Ix-low the ground line of the buildings. 
 This inequality of depth was rendered necessary by the slope of the 
 original hill on which the Caj)ilol is built. In descending from the 
 eastern frf)nt, where the foundations are drej)c(?t, the declivity was 
 made in steps, so as to preserve, in every part, a horizontal bearing. 
 The character of the earth under all the walls is the same throughout 
 the work, being a stratum of hard and com[)act gravel of several feet in 
 thickness. 
 
 In all cases the footings arc at least two feet broader than the walls 
 they support, and in order to insure the [xrmanency o( tlie western 
 fronts of both buiUlings, where the foundations were of such extraordi- 
 nary depths, the front walls and the portico walls were united at the 
 base, thus making a solid foundation o\' twenty feet in width, which was
 
 6 
 
 carried up ri^ht foot from llio footings before the walls were set off to 
 tlieir roqnirccT thii'kness. 
 
 In t]iiiL:;inG: lor llie wostorn foundations of tho soulli wing, we found, 
 at a ilepth of thiyly tcet below the level of the ground on the eastern 
 front, architectural fragments, charred timber, and other debris, from 
 the burning of the Capitol in the year 1814, which indicates the great 
 amount of tiUing up that lias been done since that time. After passing 
 through tliese masses of rubinsh, the natural earth was reached at the 
 deptli o'i thnty-cight feet below the ground line, and at two feet below 
 this undisturbed surface the walls were founded, as before stated. 
 
 The stones of which these foundations have been constructed were 
 tested, at the request of a special committee of the House of Represen- 
 taties, bv the late Professor Walter R. Jc^hnson, whose report is hereto 
 appended. 
 
 The contractors for furnishing the marble commenced operations at 
 their quairies in Lee, Massachusetts, immediately after the passage of 
 tlie ap|)ropriation l)ill, and their first cargo arrived on the 5th of July 
 last, since which time they have delivered (ivcnty cargoes, containing in 
 the aggregate 35,236 cubic ieet, making an average of 1,4S7 cubic feet 
 per week, which is quite as fast as we now require it. 
 
 Before this marble was adopted for the extension of the Capitol, it 
 was deemed proper to test the several specimens offered for the work, 
 tor the purpose of obtaining reliable data on which to make the selec- 
 tion. A commission was accordingly appointed to make the neces- 
 sary' experiments, and on their report, together with the sanction of the 
 Committees on Public Buihlings and Grounds of b(jth Houses of Con- 
 gress, the marl)le we are now using was adopted. The report of the 
 commission is hereto annexed. 
 
 In conformity to the proviso contained in the first section of the act of 
 Congress approved August 31, 1852, I appointed Mr. John C. Hark- 
 ness as measurer of all the work and materials of the extension of the 
 Capitol, and Mr. Cornelius Jacobs as receiver ot" materials on the 
 north wing and Mr. WiUiam J. Smith on the south wing, all of whom 
 were duly sworn into office. 
 
 Mr. Harkness has since measured all the work done and materials 
 furnished by contract from the commencement of" the work, and re- 
 jKDrted the same to this ofhce, in conformity to tlie aforesaid act of Con- 
 gress, and no further payments were made until the said measurement 
 was received, and the accounts presented in accordance therewith. 
 By an act of Congress approved September 30, 1850, there 
 
 was ap[)roj)riated for the extension of the Capitol the 
 
 sum of 8100,000 00 
 
 And by an act approved April 14, 1852, the further sum of 500,000 00 
 
 Making ihe whole amount appropriated for this work to the 
 
 present date 600,000 00 
 
 The amount expendf;d at the date of my last annual report, 
 
 (December 23, 1851,) was ' $88,082 86
 
 7 
 
 Since which time have been expended, to the present date, 
 
 (December 1, lS-52,) $407,717 11 
 
 Making 495,799 97 
 
 Which leaves an unexpended balance of. 104,200 03 
 
 600,000 00 
 
 A detailed account of the expenditures up to the 31st of the present 
 
 month inclusive, will be transmitted to you on the 1st of January en- 
 
 sumg. 
 
 There will be required to carry on the work during the 
 present fiscal year, ending June 30, 1853, the additional 
 sum of. $400,000 00 
 
 And during the ensuing fiscal year, ending June 30, 1854 600,000 00 
 
 Making 1,000,000 00 
 
 Library of Congress. 
 
 Immediately after the destruction of this portion of the Capitol by 
 fire, which occurred on the 24t}i of December last, I was requested by 
 the Commissioner of Pulilic Buildings to make an examination in refer- 
 ence to the extent of the injury, to report thereon, and to prepare plans 
 and estimates for repairing the damage. 
 
 On the 27lh of J;muary I submitted a design flir reconstructing the 
 principal apartment of tlie library wiiliin its original hmits, witli such 
 an arrangement as would admit of its luturc enlargement, together with 
 a report and an estimate, all of which were subsequently transmitted 
 to the Senate Committee on Public Buildings and Grounds, and on the 
 19th of ^^arch last, an act was passed by Congress appropriating the 
 sum of 872,500 for carrying out the design. 
 
 As the plans contemplnted the execution of the entire work of iron, 
 proposals were invited horn several establishments which were sup- 
 posed to possess undoubted rir;iliti(\s l()r working in that material with 
 expeditif)!) and aceuraev, ;ind the cf)iitraet w;is finally ;i\v;n'ded to 
 Messrs. Junes, lieebe & Co., of N(nv York, they being the lowest bid- 
 ders. Articles of agreement were entered into by the p.irties on the 
 21st of June last, .uid the work was commenced as soon as the j)atterns 
 could be prepared. 
 
 The gre.'it inconvenience occasioned by the lossof tin? il)rnier liijr.'uy 
 rendered it highly important to have the room fniished, if possible, be- 
 fore the asseml)ling of Congress, and to efii'ct this oiyect every possible 
 exertion has been used. The eontrncrtnrs li;ive kept as mnny men con- 
 stantly emplovefl, day and nifjht, ris the nriture of the work would ad- 
 mit, and have left no means unemployed to bring it to a speedy con- 
 clusion. Several weeks were lost by unforeseen difficulties, which 
 occurred in preparing the room for the contractors; and considerable 
 time was consumed in waiting for the patterns fi)r the f)inamental 
 work, which the pattern-makers found it impossible to prepare as rap-
 
 8 
 
 idlv as ihcy wero rr(iuire(l. But not\vitli.<tandino; tliese hindrarifces, 
 wliii'h could neither ha\'c bceu loresccu nor ax'oided, the work has 
 {)roL;ressed with uuexanipled rapidity. The ceihn^, which is wholly 
 of iron, is cnlircl}' liuishcd, and thi^ alcoves and siielves will be coni- 
 j)letcd in a few days, so that but little yet remains to be done to finish 
 all the iron work. The whole t)f this immense iron room will there- 
 fore have been cast, fitted, and j)ut up in less than six months; and as 
 lar as mv own knowledge goes, it is the first room ever made exclu- 
 sively of iron. 
 
 The damage done by the fire to the western front of the building 
 has all been repaired. The moulded dressings around the windows, 
 and all the injured portions of the w;dl, the columns, and the pedestals 
 have been removed and replaced by other stone from the same quarry ; 
 so that every part of the work is rendered as permanent and free from 
 blemish as it was before the fire. Tiie sculptured panels above the 
 windows sustained no injur}', except being defaced by smoke. Such 
 portions of the inside walls as w'ere injured, were cut out and replaced 
 by new materials. 
 
 Dcscr'qit'iun of the dcsig7i. — The librar}', when completed, will em- 
 brace the entire western projection of the present Capitol. The main 
 room, which is the part of the design now being finished, is 91 feet 
 long, 34 I'eet wide, and 38 feet high. It occupies the centre of the 
 western projection, and will connect at each end with a room of cor- 
 responding height, 29 feet G inciies wide, and 70 feet 2 inches long. 
 These rooms will be fitted up with iron cases, and iron ceilings, similar 
 to those of tlie main library. They will also be roofed with copper 
 laid on iron ral'ters, and lighted by ornamenial skylights. The con- 
 nexion between the centre and the end rooms will be made by open- 
 ings of 10 feet in width by 2S feet G inches in height, crowned by ellip- 
 tical ardies. These ojicniiiL's are already formed in the walls, so as 
 tf) admit of being cut through with but little labor. There will also be 
 two additional apartments, each IS feet G inches by 35 feet, one of 
 which is now temporarily occupied by the library; thus forming a suite 
 o\ five rooms, embracing an extent of 302 feet. These smaller apart- 
 ments will be approj)riated to the use of Senators and members of the 
 House of itepn.'scntalives as private Heading rooms. 
 
 The entire f)lan cannot, however, be carried out until accommoda- 
 tions are provided in the new wings for the officers of Congress, and 
 the committees now occupying the north and south rooms of the west- 
 ern projection. _l 
 
 The main library room, which, as before stated, is now nearly com- I 
 
 pleted, embraces the space occupied by the old library before the fire. I 
 
 On both siflcs of the rofjm are three stories of iron cases, each 9 feet 6 
 inches in height. The lower story consists of alcoves projecting 8 feet 
 6 inches into the r(jom, with cases on each side of the projections. The 
 second story hfis similar fdcoves, excepting that their projection is but 
 5 feet, which leaves a platform of 3 feet G inches in width, resting on 
 the ca-ses below, and which constitute a commodious gallery. A simi- 
 lar platform is constructed (jn the alcoves of the second story, ff)rming 
 a gallery to approach the upper cases ; thus making three stories, reced- 
 
 I 
 
 I
 
 9% 
 
 ing as they ascend. These galleries are continued across the ends of 
 the room, where they are supported by massive brackets. 
 
 The alcoves are nine feet eight inches in width, from centre to centre, 
 with an ornamented pier forming the head of each projection. The 
 architraves whicli cross the alcoves are finished with shields, crowning 
 bands and corner ornaments. The shields are designed as tablets to 
 receive the names of the general subjects on which the books in the 
 respective alcoves treat. 
 
 The galleries are all floored with cast iron plates, and protected by 
 pedestals and raihngs; they are approached by two semichcular staii- 
 ways of cast iron, recessed in the end walls of the room. 
 
 The ceiling is wholly composed of iron ; it is suspended from strong 
 iron trusses, which likewise constitute the support of the roof; it rests 
 on twenty-four mass}^ consoles, ornamented with foliage, fruits, and 
 scrolls. Each of these consoles weighs nearl}^ a ton. Their projection 
 from the face of the walls is five feet six inches, their height five feet 
 four inches, and their width twenty-one inches. The entire ceiling is 
 divided into deeply sunken panels, and embellished with ornate moul- 
 dings and foliated pendants. 
 
 The room is lighted, in addition to the Jive windows in the western 
 front, by eight sky-hghts in the ceiling, each six feet square in the clear, 
 filled in with ornamented glass, and protected by an upper sky-hght 
 of seventy-seven feet in length by ten feet six inches in width, placed 
 on a corresponding angle with the roof, and covered with thick plates 
 of glass. The roof is covered with copper, secured by copper wire to 
 the iion rafters. 
 
 Tiie furnaces for warming this portion of the building are completed, 
 and in operation. They consist of hot water pipes enclosed in cham- 
 bers erected in the old furnace room in the cellar, and connected with 
 boilers for heating the water. The external air is admitted into these 
 chambers, where it is warmed and conveyed b\- flues into the library, 
 and such of the adjacent rooms as were heated by the old lurnaces. 
 
 By an act of Congress, approved March 19, 1S52, there 
 was a[)))ropriated for "the repairs of the Congressional 
 
 Library" the sum of. $72,500 00 
 
 (Jf whicli there have been expended, to the present dale, 
 
 (Dec.l, 1802,) 51,703 24 
 
 Leaving an unexpended balance of. 20,7 9G 76 
 
 A deta.il(;d account of tlie expenditures up to tlie 31st of the present 
 month, inclusive, will be transmitted to you on the 1st of January en- 
 suing. 
 
 The Patent Office Buildings. 
 
 The interior of the cnstern wing of the Patent Office is nearly com- 
 pleted, the basement and the principal story being now re.idy for oc- 
 cupancy, and the up[)er, or exhibition room, recjuiriiig but the finishing 
 coat of plastering, the painting, and the finishing of the tiling of the
 
 If 
 
 (k>or?. Tlie hot water furnaces are completed and ready to be put 
 into operation. 
 
 Tlio eastern portico is nearly finished, and the steps and cheek 
 Mocks are all wrought and ready to be set; it will, therefore, recjuire 
 but a lew weeks to complete this part of the building also. 
 
 The work was resumed on the western wing in the monlli of Sep- 
 tember, according to the plans which were laid before you with my 
 last annual report, and the granite sub-basement is now being con- 
 structed. 
 
 THOMAS U. WALTER, 
 
 Architect of Public Buildings. 
 Hon. Alkx. H. H. Stuakt, 
 Stcrctanj oj the Interior. 
 
 Report of the Commission appointed hj the Department of the Literior ^^to 
 test the sevfral specimens (f marble offered for the extension of the United 
 States Capitol.'''' November 3, 1851. 
 
 Washington, D. C, December 22, 1851. 
 
 Sir: The commission to which has been referred the examination of 
 the marbles oflered for the extension of the Capitol, have been informed 
 that vou are tlesirous of obtaining, as soon as j)ossible, such information 
 as will enable the government to determine which of the several marbles 
 to adopt. Though the questions proposed to the commission appear to 
 ])e simple and easy of solution, yet they have been attended with many 
 difficulties; and, notwithstanding the commission have pressed on the 
 experiments as rapidly as the nature of the investigations would per- 
 mit, and have devoted more time to the subject than they could well 
 spare from their official duties, they are not yet able to present as many 
 definite results as they could desire. 
 
 In view, howrver, of the [)ressing demands for lnf()rmation, they have 
 concluded to make the fJjUowing re[Mjrt of progress, which will be suf- 
 ficient for the innnediatc action of government; and they would respect- 
 fully ask for permission to continue their investigations, and to embrace 
 in thrrn a greater varifty of the building mnterials of tliis country. 
 
 Though the art of building has been practised from the earliest times, 
 and constant demanrls have been nifide, in every age, for the means of 
 determining the best materials, yet the process of ascertaining the 
 strength and durability of stone appears to have received but little defi- 
 nite scientific atteiuion, anrl the commission, who have never before 
 made this subject a special object of study, liave been surpris(.'d with 
 unforeseen difficulties at every step of their progress, and have cr)me to 
 the conclusion that the processes usually employed for solving these 
 questions are still in a veiy unsatisfactory state. 
 
 It should be recollected that the stone in the building is to be exposed 
 for centuries, and that the conclusions desired are to be drawn from 
 results produced in the course of a few weeks. 
 
 Besides this, in the present state of science, we do not know all the
 
 11 
 
 actions to which the materials are subjected in nature, nor can we fully 
 estimate the amount of those which are known. 
 
 The solvent power of water, which even attacks glass, must in time 
 produce an appreciable effect on the most solid material, particularly 
 where it contains, as the water of the atmosphere always does, car- 
 bonic acid in solution. The attrition of siliceous dusts, when blown 
 against a building, or washed down its sides by rain, is evidently ope- 
 rative in wearing away the surface, though the evanescent portion re- 
 moved at each time may not be indicated by the nicest balance. An 
 examination of the basin which formerly received the water' from the 
 fountain at the western entrance of the capitol, now deposited in the 
 Patent Office, will convince any one of the great amount of action pro- 
 duced principally by water charged with carbonic acid. Again, every 
 flash of lightning not onlv generates nitric acid — which, in solution in 
 the rain, acts on the marble — but also by its inductive effects at a dis- 
 tance produces chemical changes along the moist wall, which are at the 
 present time beyond our means of estimating. Also, the constant vari- 
 ations of temperature from day to day, and even from hour to hour, give 
 rise to molecular motions which must aflect the durabihty of the mate- 
 rial of a building. Recent observations on the pendulum have shown 
 that the Bunker Hill monument is scarcely for a moment in a state of 
 rest, but is constantly warping and bending under the influence of the 
 var3-ing temperature of its ditterent sides. 
 
 INIoreover, as soon as the pohshed surface of a building is made rough 
 from an)'' of the causes aforementioned, the seeds of minute lichens and 
 mosses, which are constantly floating in the atmosphere, make it a place 
 of repose, and from the growth and decay of the nicroseopic plants 
 whicli spring from these discoloration is produced, and disintegration 
 assisted. 
 
 But perhaps the greatest source of the wearing away in a diniMte 
 like ours, is that of" the alternations of freezing and thawing which take 
 pkice during the winter season; and though this elU'ct must be com- 
 parativ(;ly j)o\verful, y(;t, in good marble, it requires the accumulated 
 efl[ect of a nunil)er (jf years in order delinil(.'ly to estimate its amount. 
 From all these causes, the commission are convinced that the only en- 
 tirely reliable means of ascertaining the comparalive capability of mar- 
 ble to resist the weather is to study the actual ( lli'c-ts of the ainiosphere 
 upon it, as exhibited in buildings which f()r years ha\'e been exposed to 
 these influences. Unf()rtunately, liowevcr, in this couniiy, bm lew oj)- 
 portunilies for apj)lying this test are to be loimd. Ii is line sonic ;iii;il- 
 agous itilormatioii iiiav be derived from the exainination ol the e.\])ose(i 
 surfiices f)f" marble in their out-crops at the (jiiarry ; liiit in this case the 
 length fit" time they liave been exposiMl, and the changes of actions to 
 which tiiey may have l)een subjected dining, j)erhaps, long geological 
 periods, are miknown; and since diflircnt (juarries may not have been 
 exposed to the same action, they do not always afli^rd dclinite d.ita for 
 reliable comparative estimates of durability, except wh< r<^ dilierenl 
 specimens occur in the same (juarry. 
 
 As we have said before, tlic art of testing the finality of stone for 
 buihlirii; pnrposes is at present in a very imperti'ct slate; the object is 
 to imitate the operations of nature, and at the same time to hasten the
 
 12 
 
 effect by incrcnsiinG; the energy of the action, and, after all, the result 
 may be doenied but as approximative, or, to a considerable degree, 
 merely ]iroiiable. 
 
 Ai)()ul twenty years ago an ingenious process \\as devised by M. 
 Brard, which consists in saturating thestoiieto be tested with a solution 
 of the sulphate of soda. In drying this salt crystallizes and expands, 
 thus )>r()dneing an exfoliation of surfice which is supposed to imitate 
 the eHect of frost. Though this process has been much relied on, and 
 generally employed, recent investigations made by Dr. Owen lead u& 
 to douT^t its perfect analog}'^ with that of the operations of nature. He 
 found that the results produced by the actual exposure to freezing and 
 thawing in the air, during a ])orti()n of winter, in the case of the more 
 porous stones, produced vcr}' diilerent results from those obtained by 
 the drying of the salt. It appears from his experiments that the action 
 of the latter is chemical as well as mt^hanical. 
 
 The commission in consideration of this have attempted to produce 
 results on the stone by freezing and thawing by means of artilicial 
 cold and heat. This process is, however, laborious; each specimen 
 must be enclosed in a separate box fitted with a cover, and the amount 
 of exfoliation produced is so slight that in good marble the operation 
 requires to l)c repeated many times before reliable comparative results 
 can be obtained. In prosecuting this part of the inquiries unforseen 
 difficulties have occurred in ascertaining precisely the amount of the 
 disintegration, and it has been found that the results are liable to be 
 vitiated by circumstances which were not foreseen at the counnence- 
 ment of the inquires. This part of the investigation, ihcrelbre, will 
 require a long series of experiments in order to obtain results entirely 
 reliable. 
 
 It would seem at first sight, and the commission when they under- 
 took the investigation were of the same opinion, that but little difficulty 
 Would be found in ascertaining the strength of the various specimens 
 of marbles. In this, however, they were in error. The first difficulty 
 wliich occurred was to procure the j)roper instrument for the purpose. 
 On examining the account of that used by Rennie, and described in 
 the Transactions of the ]{o3'al .Society of London, the commission 
 fi>und that its construction involved too much friction to allow of" definite 
 comparative results. Friction itself has to be overcome as well as the 
 resistance to compression, and, since it increases in proportion to the 
 pressure, tlie stronger stones would appear relatively to withstand too 
 great a comj)ressing force. 
 
 The commission first examined an instrument — a hydraulic press — 
 vrhich had jireviously been used for experiments of this kind, but found 
 that it was liable to the same objection as that of the machine of 
 Rennie. They were, however, extremely fortunate subsecjuently in 
 obtaining, thrrjugh the p(jliteness of" Comniodore Ijallard, commandant 
 of the navy-yard, the use of an admirable instrument devised by Major 
 "Wade, late of the United States arrny, and constructed under his di- 
 rectirm for the purposf; of testing the strength of gun metals. This 
 instrument consists of a compound lever, the several fulcra of which 
 are knife edges, opposed to hardened steel surfaces. The commission 
 verified the delicacy and accuracy of the indications of this instrument
 
 13 
 
 by actual weighing, and found, in accordance with the description of 
 Major Wade, the equihi^rium was produced b}' one pound in opposition 
 to tico hundred. In the use ol this instrumejit the commission were 
 much indebted to the experience and scientific knowledge of Lieutenant 
 Dahlgreen, of the navy-3'ard, and to the Hberahty with which all the 
 apphances of that important public estabhshment were put at their 
 disposal. 
 
 Specimens of the different samples of marble were prepared in the 
 form of cubes of one inch and a half in dimension, and consequently 
 exhibiting a base of two and a quarter square inches. These were 
 dressed by ordinary workmen with the use of a square, and the oppo- 
 site sides made as nearly parallel as possible by grinding by hand on a 
 flat surface. They were then placed between two thick steel plates, 
 and in order to insure an equahty of pressure, independent of any 
 want of perfect parallelism and flatness on the two opposite surfaces, 
 a thin plate of lead was interposed above and below between the stone 
 and the plates of steel. This was in accordance with a plan adopted 
 by Rennic, and that which appears to have been used by most, if not 
 all, of the subsequent experimenters in researches of this kind. Some 
 doubt, however, was expressed as to the action of interposed lead, 
 which induced a series of experiments to settle this question, wlien the 
 remarkable fact was discovered that the yielding and aj)proximatcIy 
 equable pressure of the lead caused the stone to give way at about 
 halt the pressure it would sustain without such an interposition. For 
 example, one of the cubes precisely similar to another, which witli- 
 stood a pressure of upwards of 60,000 pounds when placed in imme- 
 diate contact with the steel plates, gave wa}^ at about 30,000 with lead 
 interposed. This remarkable fact was verified in a series of experi- 
 ments, embracing samples of nearly all the marl)lcs under trial, and in 
 no case difl a single exception occur to vary the result. Tlic exj)lnna- 
 tion of lliis remarkable phenomenon, now that it is known, is not dilii- 
 cult. Tlie stone tends to give way by Ijulging out in the centre of 
 PAch of its four perpendicular faces, and to l()riri two pyramidal figures 
 with their apicf!S opposed to each other at the centre of the cube and 
 tlieir bases against the steel plates. 
 
 In the case where rigid C(juabl(! pressure is employed, as in tliat of 
 the thick steel plate, all parts must give way together. I'.ut in iliat of 
 a ycilding equable pressure, as in the case of interposed lead, the stone 
 first gives way along the lines of least resistance, nnd the remaining 
 pressure must be sustained by the central portions luound the vertical 
 axis of the cube. 
 
 After this important fnct was clearly determined, lend and all oiher 
 interposed substances were discarded, and a method devised by which 
 the ut)per and lower surfacr-s of the cube could be ground info j)er(i'Ct 
 parelleli.-ni. This consist:* in the use of a rectangular iron frame, into 
 which a row of six of the specimens could be fastencfl by a screw at 
 the end. The upper and lower snrfices (»f this iron frame were 
 wrought into perfect parallc-lism by the operalif)n of a j)laning machine. 
 The stones being fastened into this, with a small [xution of the njjjxr and 
 lower parts projecting, the whole were ground down to n flat surface, 
 until the iron and the face of the cubes were thus brought into a conlinu-
 
 u 
 
 ous iihuu". The frame was then turned over, and the opposite surfaces 
 frrouiid in hkc manner. Care was of course taken that the surfaces 
 llius reduced to perfect parallehsm, in order to receive the action of the 
 machine, were jiarallcl t(» the natural beds of the stone. 
 
 All the specimens testetl were subjected to Uiis process, and in their 
 exposure to pressure were found to give concordant results. The 
 crushing force exhibited in the sul)j()ined table is much greater than 
 that heretofore given for the same material. 
 
 Tlic commission have also determined the specific gravities of the 
 dirterent samples submitted to their examination, and also the quantity 
 of water which each absorbs. 
 
 The}'^ consider these determinations, and particularly that of the re- 
 sistance to crushing, tests of much importance, as indicating the cohe- 
 sive force of the particles of the stone, and its capacity to resist most of 
 the intluences before mentioned. 
 
 The amount of water absorbed may be regarded as a measure of the 
 antagonistic force to cohesion, which tends, in the expansion of freezing, 
 to disintegrate the surface. In considering, however, the indication of 
 this test, care must be taken to make the comparison between marbles 
 of nearly the same texture, because a coarsely crystallized stone may 
 apparently absorb a small quantity of water, while in reality the cement 
 which unites the crystals of the same stone may absorb a much larger 
 quantitv. That this may be so was clearly estabhshed in the experi- 
 ments with the coarsely crystalized marbles exaniined by the commis- 
 sion. When these were submitted to a liquid which slightly tinged the 
 stone, the coloration was more intense around the margin of each crys- 
 tal, indicating a greater amount of absorption in these portions of the 
 surface. 
 
 The following table exhibits the average of the results which have 
 been obtained, and, although they do not give the data for estimating 
 with absolute certainty precise relative values, yet they enable the com- 
 mission to pronounce, with consideraide confidence, that the first four 
 mur/jlf.i (ire of a superior (jmilidj, and, it is believed, will 2)rove sufficiently 
 durable firr the work proposed. 
 
 Column No. 1 gives the relative resistance to crushing per square inch, 
 in pf)unds avoirdupois, deduced from the average of five specimens of 
 each s.imple. 
 
 Cohnnn No. 2 gives the specific gravity of each specimen in its natu- 
 ral condition, without allowing for thr water absorbed. An allowance 
 on this account would slighlly cluinge the numljers presented. 
 
 Column No. 3 gives the wriglit per cubic f()ot in {)f)nnds avoirdupois. 
 
 Column No. 4 gives the (iu;intity of water ab.«orl)ed under a pressure 
 of about fourteen pounds to ihe square inch, produced by placing the 
 stone under water in the vacuum of an air-pump, and afterwards let- 
 ting on the pressure of the atmosphere. 
 
 Column No. 5 gives the relative amount of material thrown off in 
 freezing and thawing twenty-eight times in succession. 
 
 The quantities in the last two columns are expressed in weights of 
 which the unit is the ten-thousandth part of an ounce. These of the 
 last column are so small that the commission would prefer to repeat the 
 experiments with a larger number of specimens, subjected to a greater
 
 15 
 
 number of alternations of freezing and thawing. It will be seen, how- 
 ever, that the results coincide in a considerable degree with the cohe- 
 sive force, as exhibited in the resistance to crusliing, and also with the 
 specific gravity. 
 
 By running the eye down the column, it will be seen that the several 
 stones may be divided into two classes; the Hist four specimens of the 
 table exhibit a high power of resistance to crushing, and a high spe- 
 cific gravity. In the remaining eight specimens, there is a sudden 
 diminution in the resistance to crushing, and also in the specific gravi 
 ty. The same change exists, though in a less marked degree, and with 
 some exceptions, in the last column ; and when we take into consider- 
 ation the facts which we have stated in regard to absorption by a fine- 
 grained marble, in comparison with one of a coarsely cr3^stalline struc- 
 ture, the results in the fourth column are also not discordant. 
 
 It must be understood that the results given by the commission re- 
 late exclusively to the particular specimens which were placed in their 
 hands as the samples whicli accompanied the bids. From these spe- 
 cimens the cubes experimented on were cut under the direction of the 
 commission, and the remainder of the blocks deposited in the Smithso- 
 nian l)uilding, where they may be examined by those who are inter- 
 ested in the investigation. 
 
 It should, moreover, be stated, that the commission, as a body, have 
 had no opportunity of examining the stones in masses in the quarries, 
 or of ascertaining whether they could bo obtained in sufficient quanti- 
 ties, and of the same qualities as the specimens which have been 
 tested. Also, whether they exhibit the presence of sulphuret of iron, 
 or other contaminating substances, or show evidence of cracks or other 
 unsoundness, all of which are observations of importance in dctermLn- 
 ing the above.
 
 IG 
 
 The following is a table of the mnrblcs submitted to trial by the 
 commission, iirraiigcd in the order of resistance to a crushing force: 
 
 
 
 TABLE. 
 
 
 
 
 
 
 Origmal Nos. of samples. 
 
 1. 
 
 2. 
 
 3. 
 
 4. 
 
 5. 
 
 Localities of quarries. 
 
 Ciiisliing force on a 
 square inch, in 
 pounds avoirdu- 
 pois. 
 
 Specific gravity. 
 
 Weight per cubic 
 foot, in pounds 
 avoirdupois. 
 
 Absoqnion of water, 
 in ten-thousauths 
 of an ounce. 
 
 LoFS by freezing, in 
 ten-thousauths of 
 an ouuce. 
 
 East Chester, New York 
 
 1 
 
 3 
 
 9 
 
 7 
 
 4 
 
 6 
 
 2 
 
 12 
 
 11 
 
 10 
 
 5 
 
 8 
 
 23. 917 
 
 22. 702 
 
 IH. 941 
 
 18.061 
 
 10. 382 
 
 9. 625 
 
 9.544 
 
 9.071 
 
 8.950 
 
 8.812 
 
 8. 0.57 
 
 7. 153 
 
 2. 8579 
 2. 8620 
 2.8613 
 2. 8605 
 2.7143 
 2. 7086 
 2.7129 
 2.7131 
 2.7115 
 2. 7129 
 2.7128 
 2.7089 
 
 178. 62 
 178. 87 
 178. 83 
 178. 78 
 169. 64 
 169. 29 
 169. 56 
 169. 57 
 169.47 
 169. 56 
 169. ,55 
 169. 31 
 
 39J 
 103 
 66 
 52J 
 68 
 55 
 92 
 70,i 
 
 «!•* 
 
 87 
 
 43J 
 
 119§ 
 
 6.2 
 9.9 
 
 
 11.8 
 
 Baltimore, small crystal 
 
 West Stockbridge, Mass 
 
 Baltimore, medium crystal 
 
 "^^■(•Tnniit ^fnss ...... ...... 
 
 8.1 
 
 8.8 
 
 13.6 
 
 15.7 
 
 West Stockbridge, Mass 
 
 Montgomery county. Pa 
 
 Stockbriilgc, Mass 
 
 Baltimore, large crystal 
 
 T jpnoT Af iiss ... ............. 
 
 (*) 
 8.8 
 25.7 
 21.9 
 24.1 
 
 
 
 Respectfully subnii 
 
 •Ree 
 
 ttod, 
 
 ult lost by a 
 
 ccident. 
 
 
 
 
 Hon. Alex. H. H Stuaut, Secretary of the Interior. 
 
 JOS. G. TOTTEN. 
 JOSEPH HENRY. 
 THOMAS EWHANK. 
 A. J. DOWNING. 
 TllOiLVS U. WALTER. 
 
 Report of rrrtfcxsor TVtiltcr R. Johnson on the hiildhig stone vsed in con- 
 structing the foundutions of the extension <f tlic United States Capitol, 
 made at the request of a select committee of the House of RcpreseyUatives, 
 consisting (f Hon. John McXair, Hon. J. M. H. Beale, Hon. .Tames H. 
 Duncan, Hon. Daniel JVallace, and Hon. Thomas A. Hendricks. 
 
 Washinctox, D. C. March 11, 1852. 
 
 Gextlemex: In confornjity with your directions, in.structing me to 
 test the stone used in the Ibundation walls of the extension of the Cap- 
 itol, with respect to their strength and durability, I have the honor to 
 state that immediately after receiving your directions I proceeded to 
 inspect the walls of the two wings, and to note, as lar as practicable, 
 the general character, and the apparent differences in the stones which 
 have actually been laid in the walls. 
 
 I had no difficulty in ascertaining that some diversity, both in ap- 
 pearance and texture, existed among the materials, and it consequently 
 became evident that no one sample wtiich could be selected would ad- 
 equately represent the entire mass
 
 17 
 
 It therefore became necessary to select a moderate number of sam- 
 pics, from different parts of the two wings, and, as far as practicable, 
 with reference to the proportions in which they seemed to prevail in 
 the walls. 
 
 It is evident that this proportionality could only be approximately 
 obtained. 
 
 It is confidently believed that the extremes of character have been 
 reached, but I should remark that the sample which was taken to show 
 the least probable strength was one of a very few wliich appear mostly 
 in the foundation of the south wing. 
 
 Three samples were taken from the walls of each wing, besides 
 which a block lying within the north wall was taken to furnish a series 
 of cubes of different sizes to test the question of increase of resistance, 
 according to enlargement of area, and one sample of the sandstone used 
 in two or three of the interior projections onl}^ of the walls of the south 
 wing. This sandstone is of the same character as that of which the 
 Capitol is built. 
 
 The samples w^ere prepared for trial by sawing out from each six 
 cubes of one and a half inch on a side, which were all carefully dressed 
 by rubbing down in the ordinary manner, and the faces which were to 
 receive the compressing force were made parallel, and all the speci- 
 mens of very nearly the same height, by finishing within a steel frame, 
 which enclosed and held all the six specimens at the same time, and 
 which being turned over after dressing one set offices, allowc^d tlie op- 
 posite set to be rubbed in like manner, and made parallel to the first. 
 
 This frame is understood to be the same which was employed by 
 Messrs. Totten, Henry, Ewbank, and Walter in their rcxHMit trials of 
 the marbl(!S.* Of the six cubes from each sample, one was selected 
 and reserved for trials of atmospheric effects, and the others careliilly 
 guaged to the thousandth part of an incli, pre[)aratory to the opi'ration 
 of crushing. In general the specific gravity of every specimen was 
 taken in the ordinary way before crushing. 
 
 For the sandstone it was found necessary to take account of the 
 water absorbed when immersed for the pinpose of taking its specific 
 gravity. 
 
 The machine used for crushing is that employed fi)r the ordnance ser- 
 vice of the navy in testing the various materials rc(|uire<l for that service. 
 
 It consists essentially (j|"a. lever of the first kind, having liilcrum dis- 
 tances of 20 to 1, acting by its shorter arm on a lever of the second 
 order, having fulcrum distances (»f" 10 to I, and, eonsrcincnily, ilie i( la- 
 tion (»f the weight aj)plied to the first lever to the lluce (exerted by the 
 second is 1 to 20^). 
 
 The fulcra of the machine are all steel knife e(lgeif,and no allowance 
 is made for friction. 
 
 The compression of the specimens, win n under trial, was ascertained 
 frfim time; to lime by suitable crdipers applied by steel plates above 
 and below the stone, and the modulus ol rcsistcnce to compression 
 
 'Tilts mfftifid of <)t)fairiinR a jicrfrcf juirnllfliMin of tho l)|rirkR whk dcviHi'iI by tlic fonimiB- 
 nion ti>r tcsrini,' the iiiiirltlcH; (in<i tin- [ilnii* nii>i|il<Ml liy (licin wrrc follnwrii tliniiiirluiiit l>y 
 Pn»fc8»or .ffihnwm in (■••iidiirting thedc I'xjiiTiujt'iitd, oh will be seen by tbcir rt'imrt whirh ina- 
 mwliaU'ly precedes tbin document. -l • U. \V.
 
 18 
 
 \v;is tlius npccrtnincd Aviili considcrnble exactness. Tliis modulus 
 vari(\>i considerably in dilioicnt san)j)I(\'^, and oven in different cubes 
 iVoni the sanii! saui])le. In order to obtain a standard of comparison ot 
 ilie different specimens of the stone ojicrated on, I tested a sample of a 
 rock, largely used in this country, and to some extent by government, 
 l()r building rnd other purposes. 
 
 This was the Quiney sienite, -svhich, as will be observed by reference 
 to the table, sustained a very high pressure before crushing. In testing 
 the action of the atmosphere on the different samples, I may remark 
 that, for the particular purpose of the foundations of the Capitol, I do 
 not consider that ihe trials of the eff(>et of frost are very important, as it 
 is understood tliat these Ibundations will, when the building is comple- 
 ted, be embanked in such a manner that frost will never reach them. 
 
 For other uses to which this stone may be applied these trials may 
 be of much importance. To some extent an exemption from water pin-- 
 colating the soil will also apply to the foundations, since the water iall- 
 ing upon the building will be mostl}' carried away by pipes and drains, 
 and the shielding of the surface by pavements or flaggings will tend to 
 keep dry the foundation walls. 
 
 I have selected for the chemical trials such of the samples as ap- 
 peared to represent the exactness of strength to resist crushing, and 
 have subjected them to such re-agents as are likely to be most efficient 
 in nature in causing disintegration or dissolution. 
 
 The two samples taken for chemical analysis were those numbered 
 one and seven of the accoinpanying table, and for a mechanical separa- 
 tion of certain mineral constituents No 5, of the same table, was chosen, 
 being one of those which appeared to have been freed from the action 
 of atmospheric influences prior to its removal from the quarries. 
 
 For some of the other samples, likewise, the effect of heating was 
 noted by way of comparison. Having visited the quarries from wliieh 
 tlje stone is stated to have been derived, 1 am enabled to state that the 
 one from which the stone for the south wing was taken is known as 
 the Smith quarry, and those from which that of the north wing is taken 
 are the O'Neill (|uarries. One of the O'Neill quarries is immediately ad- 
 jiininc' that of iSmith, and these two appear hi furnish stone of essen- 
 tially the same character. 
 
 The other (juarries of O'Neill are a few hundred feet lower down 
 the canal. At all these quarries I judge that stone may be found, rc- 
 prcs( nting every variety embraced in the scries of specimens selected 
 lijr trial from the foundati(jns of the Capitol. At all of them there is a 
 covering of greater or less depth, from one or two to ten or twelve feet of 
 soil, sand, gravel, and clayey matter, with some roffed pebbles, all of 
 which repose in beds, more or less regular, upon the upper edges of 
 the micaceous rock, worked in the quarrifs. This rock lies inclined 
 southwestwardly, in angle of about oO degrees ; and the natural beds 
 and fissures of the stone afford ]:)assage to the surface water to pene- 
 trate to a considerable distance below the upper edges. This penetra- 
 tirm has caused, in some parts, a discoloration, accompanie-d by a 
 greater oi less alteratifjii fif the consistency of the rock, the natural 
 bluish or greenish color being changed to a yellowish brown, or drab
 
 19 
 
 color ; and for about 20 or 25 feet from the top, the rock has been so 
 affected by these surface influences as to be unfit for use in building. 
 
 Below that level, varying, however, in the different strata, the work- 
 able stone is found. In some of the softer portions it appenrs that the 
 decomposition has extended further down than in adjoining firmer beds. 
 
 In breaking the blocks the depth to which atmospheric influences 
 have penetrated is in general sufficiently indicated by the color. A 
 careful inspection enables the quarryman to reject those parts which 
 have been materially affected by the influences above referred to; and 
 the large heaps of rejected matter near the quarries, evince the. neces- 
 sity and the exercise of a discrimination in the selection of such parts 
 as are fit for building purposes. The discoloration of the stone is 
 sometimes only superhcial, or extends to the depth of but a few lines. 
 The upper edges of the rock next to the covering of sand, gravel, &c., 
 aflbrd little more than a mass of micaceous sand, with barely cohesion 
 enough to bear handlino;. 
 
 The rock in its normal, or solid state, appears to occupy an interme- 
 diate place between tnoe mica slate, of which flag-stones are made, 
 and gneiss, whicli has the mineral composition of granite. This rock 
 has quartz and mica in large proportions as compared with feldspar. It 
 exhibits many nodules of quartz, nearly pure, and small garnets, toge- 
 ther with iron p3'rlte3, and m:ignetic oxide of iron. 
 
 I submit a table, exhibiting, yi/-6Y, the numl)er of samples tested; sec- 
 ond, the part of the foundation walls from which they were severally 
 taken; i/uV(/, the numbers of the several specimens taken from each 
 sample; fourth, the external characters of each specimen; fif(k, the 
 S[)eci!ic gi-avity; sixth, the weight of each sam])le per cubic f)ot, (kv 
 rived from the average specific gravity; .«c«c/i^/t, the height of each 
 6pfc;-imen crushed ; c/^A//t, the observed compression; yt/'/i^/i, the force 
 producing the observed compression; tenth, the n\\\x of the bas^j of 
 each sp -cimfni opt-rated on; eleventh, the modules ot" resistance V) com- 
 pression ytf each specimen; twelfth, the avenige modulus for each sam- 
 ple; thiribk^nth, the average crushing force per scjuare inch, in pounls; 
 fourteenth, t)ie absorption of water for c;ich smnple; and, Jiftccnlh, the 
 OSS oi' cu/ii sample by the cflc'ct of heat.
 
 20 
 
 •mTu9 B.jo 0011 "1 
 '•s.>nni (){; aiii/j.iJi HI 
 ■>qn.i II. 'Ill ''i 1 11 i(\ s^dT 
 
 •.u>Jl suiiua 
 ut ipiii JCl .!'• .'ilu-> r. 
 Aq Joiu.u j« uoihIjoshv 
 
 -suxlii)) 
 -jioATi spiinoil HI i|>)ii! 
 •bs j,h1 .i.).fri| 3iin|sii.i,) 
 
 •OIlIuiBS 1|,1B3 JOJ U0I3 
 
 -sojdiiiuo o) 3jin:i!<i3 
 -aj JO so|itpuiu dlJUJ.iAV 
 
 •ascq I13HI-1 1! JO) 
 
 spunod ui in)iss,>ii!iii(i.) 
 ut oouujsisjj JO oinpuj^ 
 
 •soqa 
 -in ajiinbif iii kuoiii 
 
 -lO.lds lO OSINI lO 1MJV 
 
 8 
 
 00 
 
 o 
 o 
 in 
 
 go o o 
 ■=9 2 
 
 oo'crsT-H" 
 
 •<r o ^ 00 
 
 1^0^03 
 
 Cl -H CI o 
 
 CO ic ro CO 
 
 ^ 
 
 o 
 
 O 
 
 o 
 
 
 o 
 
 o 
 
 o 
 
 
 ■*r 
 
 i' 
 
 •^ 
 
 
 
 
 
 i 
 
 n 
 
 o 
 
 O) 
 
 
 
 
 
 
 r" 
 
 (M 
 
 <o 
 
 n 
 
 
 
 00 
 
 f^ 
 
 o 
 n 
 
 
 
 ^ 
 
 § § 
 
 o -- 
 
 s 
 
 
 S 
 
 § 
 
 s 
 
 
 
 00 
 
 n 
 
 <o 
 
 
 o 
 
 
 s 
 
 n 
 
 ■sioilupJuiAl! 'sqi 
 UI UOI*S,IJ(llllO.) po.u.is 
 
 -qo jqi Supiipoad oojoj 
 
 o ooo 
 ooo o 
 oooo 
 
 s 
 
 'Si g 
 
 •i|.iu! UI! |o noo'oi-i 
 uiuoj-Sdjduioj poAJOsqo 
 
 13 
 
 •saqsui in 
 suaunaadj aqi jo mSiajf 
 
 OdOOO 
 
 -H o — ■ O 
 ^T *T T ^ 
 
 •siodnpjiOAU spiiiiod 
 ui )uoj aiqit J jad jqaie^w 
 
 •suaim.wds 
 aqi JO AJ!At!jd jyioad^j 
 
 OOCCO>C^ TJ< 
 I- 1^ i- O I* 
 I- t- t' OJ t- 
 
 n 
 
 ^ i 
 
 ci si 
 
 CO 
 
 00 
 
 
 CO o> ■">• u> 
 
 ^ i^ Q i^ 
 
 O Ol 00 00 
 
 OB I- I- t- 
 
 ci (Ti ej c« 
 
 
 ■5 
 
 o 
 
 e 
 
 a 
 
 : : o 
 
 a 
 
 : ; a. 
 
 
 . . a. 
 
 t-. 
 
 ■ ■ o 
 
 D. 
 
 
 
 
 t.^ 
 
 . . o 
 
 o 
 
 
 
 • ■ o 
 
 a 
 
 • • a. 
 
 b 
 
 •■a Z 
 
 
 
 
 
 
 
 3 
 
 • o « 
 
 C 
 
 ■ -r "= 
 
 
 
 6 
 
 
 ?: 
 
 • > = 
 
 a! 
 a 
 
 £25 
 
 o 
 
 
 
 3 
 
 •a 
 o 
 
 s 
 
 
 •a S2 
 s -b 
 
 N 2 1' 
 
 J. "O 
 en 
 
 s 3 
 
 ° C 
 
 (A ^ ^ >. 
 
 li s _ 
 
 .Id 
 
 c^ 
 
 rt — " 
 3 S3 
 
 ■=■ -.s 
 
 •- .2 3 
 
 Of ^' tC o 
 <_ J< Ol " 
 
 o S'o 3i 
 
 F o = 
 
 5 " E 
 
 o .^ a 
 
 '" ^ ^ 
 
 c4 a> 
 
 bo tJ 
 
 •3 (- 
 
 vt 
 
 O 
 at 
 
 i> i; o 
 
 H 
 
 ci I -u.iiui.jnds oqi |o X."'1V 
 
 .2 a. 
 « 3 
 = 3 
 = o 
 
 -I 
 
 <_ S . 
 
 C _ 3 
 
 
 » =^ o 
 
 IBS 
 
 I 
 
 3 
 CO 
 
 bs 
 
 .£■5 
 
 o 
 
 o o ^ _— g-.- 
 
 o o 3 T '7 , '" 
 
 3 - 1- - i- i o 
 
 •3 ei S -3 ■— bi-« ba 
 
 tS ~ .a: S •/. = .a: = ^ 
 
 e; C 3 3 3 -y. ;5 w H 
 
 5 ^ 3 t: •- ~ ^^ ■'' ^ 
 C 3 O g 3 3. O =-.-3 O 
 0°0C3^-0'*'-0 
 
 o o >?■ o o 
 
 •g Pi"- 
 
 o. »i 3! •J' o 
 .2 -Slot 
 
 O Ci.-— o til 
 ..^ 3 r^ o .^ 
 
 £ if <-"== 3" 
 &s ° = fe 
 
 ^ = t^ ^ ' 'r 
 
 2 a* 
 
 s 3 
 
 « <s 
 
 S . u, 
 
 O Vi « 
 
 !; 5i ■« 
 
 > 5 ^ 
 
 o •- a> o. o 
 O &. O 
 
 . .= § -S? 
 
 o '*- 5n a* 
 
 IIP 
 _^ ^ *.» 
 
 br' 5 o p 
 - = = S 
 
 ■1 « « 
 
 o 
 
 -H « n 
 
 ut 
 
 « S r: "^ 3 
 " " > t- 
 
 ■5 bir > H> 
 
 ^ — . 
 
 '■5-^ 
 
 "S 5^ — ^ H.'-.c 
 3 § 3 r>-3 
 E 2 a i o <5 
 
 S :';S a. 
 
 1: i V =f 
 
 1 - £ 1 1 
 
 c 3 § a 5 
 3 . f — .a 
 " -5 i 3 n 
 37 is "5 
 
 £ 3 5 F S 
 
 O ~ "3f5 
 
 O 3 " _ 
 
 V. c- 3 3 
 c 3 S 
 
 ii 1; " 3! 
 
 '«. i a-" 
 
 3 t: .3 •— 
 
 ■didUlISi 310 J« '0\ i
 
 21 
 
 a 
 o 
 
 CO 
 OS 
 
 00 
 
 
 
 o 
 
 
 
 
 
 O 
 
 
 
 o 
 
 
 
 
 o 
 
 
 
 o 
 
 
 
 
 
 
 
 
 o 
 
 
 
 
 o 
 
 
 
 ■* 
 
 
 
 
 
 *^ 
 
 
 
 «>, 
 
 
 
 
 ■<r 
 
 
 
 CO 
 
 
 
 
 
 
 
 
 o 
 
 
 
 
 
 
 
 o 
 
 
 
 
 
 
 
 
 o 
 
 
 
 
 
 
 
 o 
 
 
 
 
 
 
 
 
 •^ 
 
 
 
 
 o 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 f-i 
 
 
 
 l-t 
 
 
 
 
 r-( 
 
 
 e o 
 
 o 
 
 o 
 
 o 
 
 > o 
 
 Q 
 
 O 
 
 o 
 
 o 
 
 oo 
 
 o 
 
 a 
 
 o 
 
 OO 
 
 o 
 
 oo 
 
 o 
 
 o 
 
 o 
 
 2 
 
 
 
 o 
 
 o 
 
 o o 
 
 o 
 
 o 
 
 o 
 
 
 
 
 
 C) 
 
 o 
 
 ITJ 
 
 
 O 
 
 O) 
 
 n 
 
 «o 
 
 
 Cl 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ^ (O 
 
 o 
 
 ■^ 
 
 
 l€ 
 
 
 t~ 
 
 m 
 
 t^ 
 
 o o 
 
 00 
 
 P5 
 
 o 
 
 *»? Ci 
 
 r) 
 
 
 
 r^ 
 
 
 ■^ 
 
 
 
 1^ 
 
 CC CI 
 
 Oi 
 
 
 T 
 
 r* I'- 
 
 
 ?:c=3 
 
 
 o 
 
 
 
 
 <- 
 
 o 
 
 <r» 
 
 i~o 
 
 
 o 
 
 o 
 
 rjro 
 
 o 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 o«o 
 
 n 
 
 <?» 
 
 c« 
 
 f-H 
 
 ft 
 
 r~t 
 
 f-( 
 
 ^ 
 
 1— ( 
 
 
 CO 
 
 (N 
 
 ft .— t 
 
 •-< 
 
 & 
 
 gi 
 
 
 IT 
 c5 
 
 CO cc 
 C5 (Tl 
 
 O O 
 
 c c 
 
 o o 
 
 ei 
 
 CO o o 
 li — co' 
 
 o o o 
 o o o 
 coo 
 
 i-« o o 
 n at -v 
 
 
 
 —I o 
 — to 
 c^ c^ 
 
 ^ 
 
 oo>o 
 o rr (^ 
 
 •^ — <S5 
 C^ CO (M 
 
 .oo 
 
 • o o 
 
 • o o 
 
 i £ SS2 
 
 § 
 
 — « o 
 
 — I-C» 
 
 o n 
 
 CO to 
 
 o o o 
 o o o 
 o o o 
 
 -H-H rt O 
 
 <c o 
 
 -^ ^- CO o 
 -T ^T O O 
 
 L'^OC o 
 
 coo 
 
 ■V -T -T 

 
 22 
 
 In condiu'tinG; llio experiments on crusliing, the opporfiinity was cm- 
 brju'oil of ascertaining the amount of compression wliieh the stone 
 received under certain loads to which it was subjected. The observa- 
 tions have a practical bearing when applied to materials of variable 
 cliar.icter entering into tlie slime structure. 
 
 h the weakest varieties were at the same time those which could 
 bear the least compression, it might happen that the blocks of stone 
 having little strengtli to resist crushing, as well as little capacity to un- 
 dergo compr(\ssion, might be crushed and destroyed, while tlie stronger 
 kinds would be yieldiiig to' the compressing force and would be event- 
 ually brought to bear tlie whole load. If, on the contrary, tlie weaker 
 varieties were capable of yielding to compression, without linall}' giv- 
 ing way until considerably condensed by pressure, they would still 
 preserve their integrity, though so much compressed as to allow the 
 stronger stones in close proximity to them to bear more of the superin- 
 cumbent weight than belonged to the area of their bearing surfaces. 
 As the compressibility of stones may be considered to arise, in part at 
 least, from their porosity, and as the latter property measures, to 
 some extent, the power of the stones to absorb fluids, it ought to fol- 
 low, that when a stone has become porous, by a partial decomposition, 
 it should be both more compressible by a given force, and more absorb- 
 ent of iiuids than it was in its natural or unaltered condition. The 
 experiments furnish a remarkable confirmation of this view. The 
 table ])ro"ses that the samples which had been altered by partial decom- 
 position (Xos. G and 7) were nmch more compressible ; that is, they 
 gave a lower modulus of resistance by compression than any of the sam- 
 ples which were in the ordinary unchanged state of the blue rock. 
 The same altered samples were likewise more absorbent of water than 
 those which were unaltered. The following short table shows the 
 modulus of resistance and absorption of water, arranged with relcsrence 
 to increasing resistance to compression, and to the admission of water. 
 
 Number of sample. 
 
 weathered stone, 
 
 do 
 
 not weathered . . 
 
 do 
 
 do 
 
 do 
 
 Modulus of resistance to 
 
 Absorption of water in 
 
 compression. 
 
 grams. 
 
 1,400,000 
 
 5.88 
 
 1,480,600 
 
 4.20 
 
 2,205,800 
 
 1.20 
 
 3,2G.'i,400 
 
 0.90 
 
 4,.'3 18,800 
 
 0.81 
 
 5,570,500 
 
 0.G5 
 
 The differences of compressibility are obviously not solely due to at- 
 mospheric action. 
 
 It will be remarked that, instead of the usual term "modulus of 
 elasticity," I have used the expression "modulus of resistance to com- 
 pression," which seems to be more appropriate to express that charac-
 
 23 
 
 ter or property of building materials, which is practically apphed in 
 ai'chitecture. 
 
 Examinations to illustrate the effects of atmospheric injluences on the stone. 
 
 In testing the action of frost, I have appealed directly to the process 
 of freezing the specimens after moistening them with distilled water. 
 
 This mode of experimenting (not now apphed for the first time) has 
 the advantage over other processes sometimes resorted to for imitating 
 the effect of freezing, in producing both the chemical and the meclian- 
 ical actions on the stone which naturally result from atmospheric hu- 
 midity and a freezing temperature. 
 
 Each cube subjected to freezing was enclosed in a thin metallic box, 
 furnished with a suitable coverinG:, and the whole series of boxes con- 
 tammg the specimens was placed within a larger vessel of thin metal, 
 which was surrounded by a freezing mixture. Care was, of course, 
 tiiken that all the particles detached from each cube by the freezing 
 should remain in its own box. The gain in the weight f:f the box, alter 
 thirty repetitions of the freezing process, as ascertained by a balance 
 sensible to the two-hundredth part of a grain, gave the loss which the 
 stone had suffered under this treatment. Both in respect to the absorp- 
 tion of water and to the influence of frost, it will be observed that the 
 strong rocks, such as sample No. 1 of the blue quarlzose mica slate, and 
 the Quincy sieriite, (sample No. 9,) manifest great power to resist the 
 disintegrating action of these powerful causes. While sample No. 1 
 lost only t5o of a grain by frost. No. 6 lost tottj No. 7 ^Vo 'J"(l the 
 Aquia creek sandstone, No. 8, lost -1-,^;, or exactly 12 times as nnich 
 as No. 1. While the sample No. 5, a very sound and comj)act v.nicly 
 of the blue rock, absorbed but ^V of a grain of water. No. G took l.xJU, 
 No. 7, 5.88, and the Aquia creek sandstone 199 grains. 
 
 The latter acted in fact like a sponge and became completely wet 
 UnouLdiout. 
 
 This was proved by crushing some cubes of that stone immediately 
 after they li.ul been immersed in water. It is pnjper to state that the 
 absorption of water is represented by tht; dilli'rencc in weight, asccr- 
 Uiiried by first weighing the specimens afUT being thoroughly dried, 
 and ag;iin aflir being permitted to absorb water by the aid of the 
 exhausiion of an air jjump, and the sub.-cijuent j)icssure of the atmos- 
 phere while immersed in a vessel of water within the receiver. 
 
 Chemical and other cxaminatioris to ascertain the vffccts of the atmosj)here. 
 
 I have not sought to determine the exact relations of llie insoluble 
 ingredients of the rock to each other, since neiih* r in ;i |)ractit;al nor 
 theoretical view would the information thus obtained be of much 
 value. 
 
 The rock is comjjoundcd of a vari(;ly (»f different miiier.ds, .uid 
 may be termed a quartzcjse mica slate, in which the (juartzose constit- 
 uent varies from point to j)oiiii, and the garnets and other silicious 
 minerals, usually occurring in such rocks, vary in (|uantiiy i" dllli rent 
 spechnens. Feldspar is less abundant, at least, far less distinctly char-
 
 24 
 
 nctcrlzcd ns such, in most of the spocimcns than mica and quartz ; 
 hence the apphcahiHly of the name in preference to tlie term ^«em. 
 
 When present feUlspar is hable to be decomposed by the action Oi 
 water, or of water impregnated with carbonic acid, taking up a part 
 of the siUcia and the potash, and leaving water in their place, as a 
 constituent in the state of hydrates of silicious compounds, and ot 
 metallic- oxides. Tlie lime of the feldspar is, at the same time, converted 
 into carbonate of lime by the carbonic acid accompanying the air and 
 water, Mhich dec;ompose the ieldspar. From this reaction comes the 
 ditlerence well known to exist between feldspar and kaolin or procehiin 
 earth, the latter of which is derived, from the decomposition of the 
 former. As the rock contains sparsely scattered particles of sul- 
 ])huret of iron, and also iron in other states, a mechanical analysis 
 was made on a specimen which was considered to represent fairly 
 the general character of the rock, in order to ascertain the per-centage 
 of that sulphuret. One of the specimens of sample No. 5 of the table, 
 which had been crushed, was taken for this analysis. 
 
 A quantity of it in powder amounting to 2747 iVo grains, was care- 
 fully examined in small portions at a time, by the aid of a strong mag- 
 net, which separated the magnetic oxide of iron. The powder was 
 then washed, and when reduced to a small quantity by floating off" the 
 lighter particles, the sulphuret of iron was easily separated from 
 among the black sand and minute garnets which remained with it. 
 The garnets had been in part collected while pulverizing the stone, 
 and with the smaller particles gathered as above amounted to 
 
 20 iVb grains 0.744 p. c. 
 
 42 grains magnetic oxide of iron 1.528 " " 
 
 16 grains iron pyrites 0.058 " " 
 
 11.8 grains black silicious sand 0.429 " " 
 
 Light black powder, which floated on immersing the pul- 
 verized stone in water 0.001 " " 
 
 Sand (silicious and micaceous) with dark colored clayey 
 
 matter 97.240 " " 
 
 100.000 
 The very trivial quantity of sulphuret of iron, found by this analysis, 
 confirms the impression conveyed by the inspection reported in column 
 4 of" the accompanying table, that the proportion of pyrites (about yy 
 part of one j)er cent.) is too insignificant to exercise any serious influ- 
 ence on tlie durability of the stone, especially as the sulphuret is not 
 collected together into veins or pockets, but is sparsely scattered 
 throughout the stone. The manganese found is probably in the state 
 of either protoxide or protochloride in the stone. 
 
 Experiments to show the relative condhum of the altered and unal- 
 tered samples of the rock in respect to water, cliemically comljined, 
 Sample number 3 was tried by placing 111 grains in fine powder in a 
 test tube, and heating a little above the boiling point of water, by which 
 0.26 per cent, of moisture was expelled. By further heating, water 
 continued to be expelled until a red heat was attained, when the quan- 
 tity had very much exceeded that driven off by heating to the boiling 
 point. Owing to accident the precise quantity was not ascertained.
 
 25 
 
 Sam-pie No. 1. Fifty gi-ains of this sample exposed for two hours to 
 a temperature of 212^ lost of moisture 0.55 grain, equivalent to 1.1 per 
 cent. 
 
 17.75 grains of the same, heated to redness for an liour, lost 0.35 
 grain, equal to 1.97 per cent. Hence the per centage of water, other 
 thaji adhering moisture, was 0.S7 per cent. 
 
 Sample No. 2. — S4.55 grains lost of moisture only 0.1 grain, or 0.118 
 per cent. After a prolonged exposure to a red heat it had lost 0.75 of 
 a grain more, equal to 0.SS7 per cent. From this it should seem that 
 the rock in its unaltered condition contains 0.875 per cent, of water in 
 chemical combination. 
 
 Sample No. 6. — Of this sample 89. 5 grains, after thorough drying, 
 had lost 0.15 grains = 0.1G7 percent.; and when subsequently heated 
 to redness for half an hour it lost in addition 1.3 grains = 1.463 per 
 cent. 
 
 Sample No. 7. — Of this, which, like the preceeding, was a weathered 
 or altered rock, 50 grains lost in drying 0.1 grain, or 0.2 per cent., and 
 another portion of the same powder of 40 grains lost, by a continued 
 ignition, 0.65 grain, or 1.625 per cent., from which, deducting moisture, 
 0.200 per cent., there remains in combination 1.425. Tlie mean of the 
 two trials on the altered stone is 1.444, from wliich, deducting the above 
 mean for samples 1 and 2, = 0.878, we have the excess of water in 
 the hydrates of the weathered stones = 0.566 per cent. 
 
 As might be reasonably anticipated, this replacement of a portion of 
 the mineral ing?-edients of the stone by water is acconip.-inicd by a di- 
 minution of specific gravity. Thus liom column six ol" ihc ibrcgoing 
 table it appears that the avernge weight per cubic l()ot of Nos. 1, 2, 3, 
 4, and 5 (unaltered stones) is 174.15 pounds, and tlie nn:in weight of 
 Nos. 6 and 7 is but 162.92 pounds. Even of this lalter weight it ap- 
 pears that 0.566 per ccril., or 0.97 j)ouii(ls, is combined water added in 
 the course r;f tlie alteration. This being (hnhietcd, k-aves of the; origi- 
 nal mineral constituents only 171.95 pounds, showing that 2fo pounds 
 of mineral per cubic foot have been extracted. 
 
 Degree of solubiliti/ of the sfn/trs in arids. — 'I'he ])ro(hicls oi llie soil, 
 such as the vcgetabli; acids derived liom the d('coMi|)o>ilioi) of plants, 
 have nr) doubt ro-operatcd nioic or less powerfully with the atmosphere 
 in i)nKlucing the alterations visiblr at tin; (juarrifs at the uj)pcr part of 
 the strata, and pcrcejjiibli; on the cxti.'rior or interior of some sam|)]es 
 at the Capitol. 'J'hc pow(,-r of tlu" stone, when laid in buildinir, to n;- 
 sist the further ucUou of acids, may be less imporlani, in n-fficnce to 
 the organic products of the soil, than win u exposed in llio (junrriea to 
 their influence beiieaili llic natural surface; Imi oiln r acids, and ihcir 
 compounds, may and do |)ro{luce on the materials ol buildinu's ctlf els 
 which, in the course of time, becouK! suiruiently marked. Had tune 
 permitted, it would jjave been desirable- to trace distinctly the inllu- 
 encc of the several causes just alludr-d to, and note the jtrccise effects. 
 But the trials would be long, minute, and labr)rious. 
 
 The followini,' trials have reference to tin; total amount ol matt(!i 
 which acids, even in their concentrated f(»rm, are capable ol dissolving. 
 Tliirty grains in powder of sample iNo 1, .after thf)roui;li drying, (where- 
 by it lost 0.1 of a grain,) were treated with strong chhjrhydric witii a
 
 26 
 
 little nitric acid, and the treatment repeated with fresli portions of acid, 
 until everything soluble appeared to be removed. The ignited residue 
 was observed to contain a few black particles, which were found to 
 be magnetic oxide of iron removabU' ijy the magnet. The residue 
 weighed 25. Go grains, or S2.17 per cent, of the original assay. Show- 
 ing that of moisture, combined water, and mineral water, there had 
 been removed 17.83 per cent. 
 
 On sample No. 7 (altered rock) 30 grains lost of moisture O.OG grain, 
 and these, by long boiling in chlorhydric with nitric acid, wasliing, 
 separating, drying, and igniting, left a residue of 2G.23 grains, of which 
 0.03 grain was magnetic oxide of iron. The insoluble part is, conse- 
 quently, 87.43 per cent, of the original weight, and the part dissolved 
 is 12.57 per cent., showing a marked diflerence between this partly 
 decomposed sample and the unaltered stone No. 1. The insoluble sili- 
 cates are, of course, left in the rock altered by natural causes, and be- 
 come a larger portion of the whole weight than in the unaltered state. 
 Of the matter in sample 1, it appears there were of insoluble percent. 
 
 silicates, with a little mametic oxide of iron 82.17 
 
 Hygrometric moisture 0.33 
 
 Combined water 0.87 
 
 Insoluble matter (silica) left in drying the solution 0.60 
 
 Peroxide of iron 6.30 
 
 Lime 0.34 
 
 ^lagnesia 0.20 
 
 Alumina 3.04 
 
 Protoxide of manganese 5.09 
 
 Potash 70 
 
 99.64 
 The above is the result of but a single analysis, which I should de- 
 sire to repeat and vary, did time permit, in order to assure myself of 
 the entire accuracy of the results. 
 
 In order to arrive at some estimate of the adecjuacy of the founda- 
 tion walls to support the structure which it is intended to place upon 
 them, I have taken from the working drawings of the architect the di- 
 mensions of the main walls already laid. These walls are, in general, 
 six feet nine inches thick, but at those parts where the walls are high- 
 est, the base resting directly on the ground, it is widened to nine feet. 
 I find that the entire circuit of each wall (not including the porticoes) 
 will be equal to a single wall 728 feet long. This wall is to support a 
 superstructure 34 feet high and 4J feet thick, composed, in part, of 
 marble weiuhing about 179 pounds per cubit foot, and in part of other 
 materials, brick, mortar, &c., which will probably weigh considerably 
 less; but I have assumed, for the sake of giving their full weight, that 
 the entire wall will weigh 175 pounds [)cr cubit foot. Conse(|uenlly, 
 one lineal foot of superstructure will weigh 20,775 pounds. This 
 weight, when transmitted to the base of the foundation walls, where 
 they are 6f feet thick, will load each square foot with a weight of 3,966 
 pounds; but where the foundation walls are 9 feet thick, the load at the 
 base due to superstructure will be but 2,975 pounds per square foot. 
 The highest part of the foundation walls themselves is stated by Mr.
 
 27 
 
 "Walter to be 40 feet, and by the accompanying table it appears that 
 the stone weighs 173 pounds per cubic foot, from wliich it follows, that 
 a vertical wall (not widened at the base) would press that base with a 
 force of 6,920 pounds per square foot, which, iiddcd to the pressure of 
 3,966 pounds, due to the superstructure, would give a total of 10,SS6 
 pounds, which would have been the load at the bottom of the founda- 
 tion wall at its deepest part, if it had not been made thicker thnn the 
 rest. If this deepest part of the foundation be gradually thickened 
 from 6f feet at the top to 9 feet at bottom, the weight of it distributed 
 over the base will be equivalent to a load of 6,05-5 pounds per square 
 foot, to which adding the weight of the superstructure, as above com- 
 puted, for the same 9 feet base, viz: 2,97-5 pounds, we obtain 9,030 
 pounds on one scjuare foot. 
 
 By a reference to the table of results of experiments on crusliing, it 
 will be found in column thirteen that of the blue micaceous stones No. 
 7 gave the lowest mean strength, viz: 8,156 pounds per square inch. 
 No. 1 gave the highest result, viz: 20,715 pounds; and the average of 
 seven samples of that kind of stone is 15,603 pounds per square inch. 
 
 8,156 lbs. per square inch is at the rate of 1,174,464 lbs. per sq. foot. 
 20,715 do do 2,980,960 do 
 
 15,603 do do 2,246,832 do 
 
 1,174,464 contains 10,886 one hundred and eight times. 
 
 2,980,960 do two hundred and seventy-three times. 
 
 2,246,832 do two hundred and six times. 
 
 If the highest part of the foundation had been built only 6? feet 
 thick at bottom, as well as at top, and wholly of the w(Nd<fsi kind of 
 stone tested, its strength would have been 5f times as great as ihe load 
 to be supported would have re(}uir(;d, according to th(! archili'cniral 
 rule in relation to walls of rough stone; and il' made 9 lid at boiiom 
 and Of at toj), having to bear, as above, 9,030 pounds j)er S(]uare loot, 
 the crushing fijrce of" tluj stone would have b(;en 6A times llic r(>(piir(vl 
 Strength. 11 constructed of stone having the avtragr sfn/ig/h of tlio 
 seven specimens of the quartz mica slate, the wall of iV^ i\'c\ thick 
 would have a strength ten and thrcc-tmtlix times as great ;i.s tin; above- 
 mentioned rule would r<(piire; and if it had a nine feet base, as be- 
 fbrf!, it would be- twelv(j and two-fifths times as strong as the rc(|nire- 
 ment of its load. 
 
 The architectural rule to which I have just r(;ferred maybe li»und in 
 Weisbacli's " Principles of the Mechanics (»f Ma( liineiy and Engineer- 
 ing," American edition, vol. 1, |)age 215. in a slalenieiit of the |)rae- 
 tical application of" the ascertained strength of" materials to resist crush- 
 ing, it is there s;iid that "ten times iIk; absolute strength is given to 
 WfX)d and stones, to iron only one of live times, and to walls of rough 
 stones twenty times. Though these foundations are not wholly <>f 
 rough stones, yet as they are so in ])art, 1 have elK)sen to assume that 
 basis of computation as entirely within th(; limits of safety, whatever 
 may be the size of the; specimens composing the masonry. 
 
 1 have thus far spoken of the force pressing on the bottom of thn 
 founrlation walls at their dee[)est part. It may, j)erlia|)S, be said that 
 the superstructure does not rest on a continuous wall, but on a fbundu-
 
 THE LIBRARY 
 
 IIWyERSJTY OF CALIFORNIA 
 
 LOS ANGELES
 
 r- mmmm 
 
 Y , ^ 1158 00392 c 
 
 UNIVERSITY OF CALIFORNIA LIBRARY 
 
 Los Angeles 
 
 This book is DUE on the last date stamped below. 
 
 
 1 ^'■■^r. I/' II '.'■ ■- <..■ : Drj-lT^^Rl-m