1848] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



75 



vated by tlie attempt made in the work under review to throw 

 dust in the eyes of the reader, by abusing- the author whose tables 

 are copied. The attacks commence in the preface, and are con- 

 tinued at intervals to the end of the book, with all the emphasis 

 wliich italics and capitals can give them. For example, speakina: 

 generally of other previous tables, our author allows that "none of 

 them are accompanied with directions for finding the contents 

 from the sectional areas, which is the most important part of such 

 tables, except JMr. Bashforth's ; but his jiiethod of applying them is 

 arrmieous." Now, the assertion, which we have given in the au- 

 thor's own italics, is not only untrue, but it would not be un- 

 cSiaritable to assert that it is put forth to disguise the real relation 

 <£ his own method to i\Ir. Bashforth's. The supposed error refers 

 to the calculation for side-long ground (or cuttings or embank- 

 ments on the side of a hill, where the height of the slopes is un- 

 equal), and is established by taking a perverse and preposterous 

 example — that of two sections, 4 chains apart, of the areas 10,321 

 feet and 400 feet, respectively. As if in a length of 4 chains, no 

 intermediate sections would be taken where the first section was 

 more than twenty-five times the last ! 



Setting aside the extra\agant nature of the case supposed, Mr. 

 Bashfortli's method, even if so applied, is just as likely to give a 

 true result as that which Mr. Baker ivould substitute. We are 

 told, that by neglecting the area of the triangle, the former 

 nrethod gives a result 7^ per cent, too small : but it is just as 

 likely that the substituted method gives the result as much too 

 great ; for the ground may undulate so much, that the error may 

 be either in excess or diminution. In a case like the present, 

 is-here the ground falls so much in the direction of length, that 

 tlie heights of one end-section are only one-fifth those of the 

 other end-section, great irregularities of surface must be supposed to 

 intervene. For instance, suppose a valley or deep hollow occurred 

 somewhere in this length of four chains of cutting, Mr. Baker 

 would tell the contractor that he had to remove all the contents 

 of the vallcj', which, in reality, nature had already excavated for him. 

 There is no guarding against such errors, except by the precaution 

 which every reasonable engineer adopts where the ground varies 

 considerably — which, in the present case, would be practically 

 inevitable — and which Mr. Bashforth's method supposes, — that of 

 taking frequent sections. 



Our worthy author has not borrowed his predecessor's table of 

 Proportional Parts, — which, as we explained in a former review, 

 is printed on card, with a moveable index of wood sliding in a 

 groove. It is estimated that by this ingenious contrivance, the 

 table is made to contain all the calculations which, extended, 

 would occupy a surface 42,250,000 times its present area. To 

 kave adopted this table also, would have been too palpable a 

 plagiarism ; Mr. Baker, therefore, contents himself with copying, 

 figure for figure, the first twenty-one lines of it, which constitute 

 te(!) " 'fable No^2 ;" 



cases wl 



the calculations for himself. 



It is not to be expected that every practical person who calcu- 

 lates quantities for contractors, should understand the mathe- 

 matical principles on which the particular tables which he uses 

 are based. But it is within the simplest comprehension, that the 

 two methods under comparison — and they alone — proceed on the 

 assumption that the slopes are hypothetically continued to their 

 intersection. It is also not a matter of reasoning at all, but 

 one of mere eyesight, that Mr. Baker has re-printed Mr. Bash- 

 forth's calculations identically. The only differences are these — 

 Mr. Baker's table is printed in a less distinct manner ; to Mr. 

 Basfortb's table of 65 heights (reprinted without a single omission) 

 se^'en more heights are added : lastly, of the table of Proportional 

 P^rts, the first twenty-one lines are reprinted , and as to the 42 

 millions and odd remaining calculations, Mhich the sliding index 

 ingeniously efi'ects — why, the reader is left to calculate them for 

 himself. 



" Table No. 2 ;" and the reader is informed (p. 48), that in 

 vhich this " Table No. 2" does not include, he must work out 



The Steam Navy. — Mr. Edward Whitley Baker has been appointed by the 

 government to go out with James Brooke, the Rajah of Sarawak. Mr. 

 Baker is attached as engineer to the Mseander frigate, and is to have charge 

 of a steam launch, to be used in getting up the small rivers and creeks for 

 surveys and in search of pirates, and is to be at the service of the Rajah in 

 Sarawak and Labuan as mechanical engineer. We are glad to see from this 

 appointment that the Admiralty are really desirous to improve the engineer- 

 ing service of the navy, by employing efficient practical men like Mr. 

 Baker. 



REGISTER OP NE"W PATENTS. 



BALANCE BRIDGE. 



John Harvey Sadler, of Holheck, Leeds, iron merchant, for 



" Improvements in constructing bridges, aqueducts, and similar struc- 

 tures r—Gvanie A July 7, 1847; Enrolled January 7, 1848. 



This invention relates to the construction of cast-iron girders 

 for continuous bridges, viaducts, or aqueducts, and other improve- 

 ments relating to railways. Fig. 1, is a side view made according 

 to this invention of cast-iron girders c, strongly jointed and bolted 

 together at a, standing upon piers of stone or brick b b b, each 

 girder c, being cast from one and the same pattern, or where no 

 very great length is requii-ed, two parts c c', may be cast as one 

 piece ; in either case from the points d, will constitute one girder, 

 which is from centre to centre of two arches, and the two parts on 



Rg. 2. 



Fig. 6. 



Fig. 4. 



•Fig. 6. 





^ 



I I 



Fig. 3. 



Fig. 7. 



either side of a bar ft, will balance each other, consequently, there 

 is no weight or sway comparatively speaking in the centre of each 

 arch. It will be seen that each girder is loose and at liberty at the 

 centre of each arch rf rf, and though strongly jointed together by 

 means of plates on each side, they will allow for any contraction 

 or expansion required by change of the atmosphere ; and fig. 2, is 

 a transverse section of this joint, showing how the toothed-plates 

 fit into similar teeth at the ends of each girder where they meet at 

 the centre. Fig. 3, is a plan of the cast-Lron flooring for bridges, 

 &c., consisting of plates of cast-iron. Fig. 4, shows these plates 

 upon an enlarged scale, the underside uppermost and not closed 

 together, the better to explain how strength may be given t'o 

 these plates to bear the rails and any weight required to pass over 

 them ; and fig. 5, i^ a transverse section, showing how these plates 

 are fastened togetJier, and bolted to the girders by the brackets 

 i i. The covering or flooring-plates e and /», are shown to be a 

 foot in width, and of the length from girder to girder correspond- 

 ing to the width required for the raUway. 



