376 



THE CIVIL ENGINEER AND ARCHITECFS JOURNAL. 



[Dko, 



face, and lastly, a good road metallinj;, of a kind approTed, of 8 inches thick, 

 shall lie laid, and the stones properly broken. 



" Where stone imposts or springers are used, they must be equal to the 

 full thickness of the arch, besides allowing; for the projection, and no stone 

 shall be less than 30 inches in length ; where there is more than one arch, 

 at least four stones on every pier shall extend across the whole breadth of 

 the pier. In cases of skew arches, the skew back must be worked out, to 

 suit the oblique direction of the courses. 



"Openings must be left through the lower parts of all abutments, wing 

 wal!s, and retaining walls, and dry rnbble drains carried up at the back, in 

 order elfectually to prevent any water lodging behind the brick work or 

 masonry. 



" The abutments and wing walls shall be filled into and backed with 

 chipping of stone, as far as they can be procured, clean dry gravel, or suit- 

 able material approved of by the engineer, and to be procured in the 

 neighbourhood ; as they are carried up, the filling and backing shall be 

 well rammed with punning malts, in courses not exceeding eighteen inches 

 thick. 



" Culverts, under three feet in length, must be carried to the outside of 

 the fencing. Culverts must be built to the necessary angle, and each culvert 

 shall be so placed as to give a free and uninterrupted passage to the water ; 

 and whenever the position or direction of a culvert does not coincide with 

 that of the existing course of stream, the course shall be altered to such ex- 

 tent as may be considered requisite by the engineer, to adapt it to the posi- 

 tion of the culvert, by the contractor, at his own cost. They shall be built 

 of materials to be approved of by the engineer, and such as will stand well 

 in water, and shall be set in good hydraulic lime mortar. The site of cul- 

 verts may be varied by the engineer. 



"The foimdations of viaducts, bridges, culverts, walls, and other works, 

 must be excavated to such depth .is the engineer may deem requisite, and no 

 masonry or concrete must be put in until they have been examined and ap- 

 proved of by the engineer. All the water must be effectually kept out during 

 the execution of the works by means of coffer-dams or pumps, or both, and 

 the cotfer-dam or pumps, or other machinery, to be provided by the con- 

 tractor, and approved of by the engineer. If it is required to carry the 

 foundations lower than shown on drawings, the contractor must execute such 

 additional masonry, brick work or concrete, or piling and planking, according 

 to the schedule of prices, being paid only for such additional work so 

 put in. 



" The piles to be of red pine timber, 10 inches square, each pile shod with 

 a wrought iron shoe, weighing at least 18 lb. ; the piles to be driven well 

 home, and at least 2 feet into a solid material, with waling pieces, 12 inches 

 by 10, bolted to them by wrought iron bolts, to which 3 inch planking shall 

 be firmly spiked. 



" The whole of the timber used in the bridges shall be of the best St. 

 John's red pine or Baltic timber, and the deals from Dantzig, of such lengths 

 as may be required, free from heart shakes, sap, dead knots, dry rot, or any 

 other defects whatsoever, and thoroughly seasoned, having been felled at 

 least two years, and six months out of water. All the trenails used in the 

 bridges shall be of sound English oak. It must be stacked as soon as brought 

 on the ground, and preserved from wet until used. All the timber must be 

 painted with three coats of good oil paint, at such times as the engineer may 

 direct. In measuring timber, no allowance to be made for mortices, tenons, 

 &c., but only the net measurement taken ; and the workmanship throughout 

 to be good, sound, and firm, and such as shall be approved of by the en- 

 gineer. 



" All castings shall be moulded of a true form, and free from air holes or 

 other defects, and shall be of correct measured dimensions when ready to be 

 titled in place. All cast iron shall be of the best No. 2 iron, re-melted in the 

 furnace, and shall be of a quality approved by the engineer ; no hot blast iron 

 will be allowed. 



" Girders shall be subject to be proved by the hydraulic press, under the 

 inspection of the engineer, and at the expense of the contractor, according to 

 what the substance and form are calculated to bear, and each girder shall be 

 tested by at least one half the calculated breaking weight. Or the iron shall 

 be of such strength, that an inch square bar, of 36 inches in length, between 

 supports, shall bear a weight of 500 lb. suspended in the centre. And, 

 should any castings be injured by testing, or prove unequal to the test, 

 others, that shall be satisfactory to the engineer, shall be provided by the 

 contractor. 



" All joints shall he made to fit perfectly close and tight, and no cement 

 stopping or plugging shall be introduced ; and in all cases where iron rests 

 upon stone, a milled pad must intervene, and the whole must be put together 

 in the best and most workmanlike manner. 



" Wrought iron must he of the best scrap, or No. 3 bar iron, approved of 

 by the engineer, and of sufficient strength to bear, without injury, 15 tons 

 per square inch of sectional area. 



" No wrought iron straps, bolts, or other work, must on any account be 

 hammered when cold, without being afterwards annealed. The bolts to be 

 made so as to fit the holes correctly, after they are seasoned to receive them. 

 All iron work must be painted with three coats of good oil paint, without 

 being allowed to rust. 



Engineer'a Manual of Mineralogy and Geology. By Sirs. Varley. 

 London : Weale. 1846. 



This is a very clever little work, well written, lucid in its descriptions, 

 and we think fully carries out the intention of its talented authoress. 

 Mineralogy is a subject of growing interest, both as a pure science, and in 

 its applications to the arts ; and a work, divested of technicalities, and the 

 intricacies of nomenclature, is a desideratum. No science has undergone 

 more revolutions in this respect, as we find many minerals have no less 

 than four or five names in dEflerent books. A knowledge of the laws, and 

 the relations of crystalliue forms, which obtain in the mineral kingdom is 

 valuable, not only as a subject of philosophic speculation, but also in its 

 applications to geology, chemistry, and especially to engineering pursuits. 

 Few men have more frequent opportunities of studying practically the 

 sciences of geology and mineralogy than engineers ; for at the present 

 time, when railways are being carried on, and the surface of the 

 earth penetrated in almost every direction, the diflferent strata, and the 

 mineralogical character of the country must be constantly under their no- 

 tice, and in the words of our authoress, " They ought in such operations 

 to compare and combine an accurate observation of whatever comes under 

 their cognizance with facts already established ; and every new incident 

 however trifling it may at first appear, if recorded with precision, will be- 

 come valuable as an addition to the geological knowledge we already pos- 

 sess." 



As an illustration of the necessity of paying due attention to the internal 

 structure of the materials used in machinery, and more particularly to those 

 parts which are subject to a long continuous vibration, we may instance the 

 alterationof structure to which the iron axles of railway carriages are li- 

 able from the perpetual vibrations to which they are exposed. The toughest 

 and most fibrous wrought iron is always selected for the construction of 

 these axles, and from this continuous vibration the particles assume a new 

 crystalline arrangement, assimilating to the construction of cast iron, and 

 eventually becoming brittle. We understand this important point is under 

 careful examination. Some very interesting specimens of iron axles which 

 have undergone the molecular changes in question, may be seen at the 

 Museum of Economic Geology. 



We will now give a brief sketch of the subjects in the work, and the 

 manner in which they are handled. The first 42 pages give a short account 

 of the rocks of Devon and Cornwall ; the unstratified rocks, granite, syenite, 

 greenstone, basalt, porphyry ; all of which belong to the trap formation with 

 the exception of granite; also the places at which they most abundantly 

 occur: then follow the stratified rocks, gneiss, mica-slate, clay-slate, the old 

 and new red sandstone formations, carboniferous and oolitic systems, creta- 

 ceous and tertiary systems, with the minerals which are found in them- 

 with a short account of the analysis of them, by that invaluable little in- 

 strument, the blow-pipe. Although we agree with the authoress that " ia 

 the greater number of cases, if a specimen of ore be characteristic, an ac- 

 curate observation of its external character will enable us to recognise it 

 without having recourse to chemical process;" yet we vpould strongly re- 

 commend students who wish to acquire a knowledge of mineralogical 

 science, first to obtain some acquaiutance with chemical analysis. A few 

 tests or re agents, combined with the application of the blow pipe, will en- 

 able them to perform a qualitative analysis of an ore, and thereby obtain a 

 much more intimate knowledge of the composition and nature of the ore 

 than could possibly be acquired by the simple observance of its external 

 characters: again, according to Mitscherlich's law of isomorphism, there 

 are minerals whose crystalline forms are identical, but whose chemical 

 composition is different. 



The different ores of gold, silver, copper, iron, &c. are next brought 

 under consideration, their characters are succinctly given, and the richest 

 ores for smelting stated. The tables of analysis of silver and copper ores 

 are valuable, as showing the amount of metal which can be extracted from 

 each one : we should have liked to have seen the same carried out for some 

 of the other metals. The next part of the work treats of the mineral rocks 

 and earths, and closes with the physical characters of minerals, embracing 

 a brief account of the doctrines of crystallography. M'e would notice the 

 only error which we have observed while perusing the work, and that for 

 the purpose of having it corrected in a subsequent edition. It is stated, 

 page 40, that gold is soluble in hydrochloric acil, whicli is a mixture of 

 nitric and muriatic acids ; now, hydrochloric arid is the new name for 

 inuriat'C acid, and as such, gold is insoluble in ; , Gold is not dissolved 

 in any of the pure acids ; its best solvenis ai t lorine and nitro-hydro- 

 chloric acid, and the latter only when it giv t.se to the formation of 

 chlorine. We miglit observe that fluorine also coi.- jines directly with gold. 

 In every other respect the work merits our most cordial approbation, and 

 our thanks are due to the lady who has produced a book which we feel 

 assured will be useful. 



