86 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[March, 



Railways, their Uus and Management. — London, Pelham Richardson, 



1842. 



This is a very interesting epitome of all the railways that have been 

 executed and in progress in this country, and is very ably written, 

 affording a brief insight into their cost, working, and management. 

 The following extract, relative to some of our principal engineers, will 

 be read with some interest. 



"Most happy should we be if the undertaking had to depend for its 

 success in Parliament upon its own value without the intervention of 

 counsel, as not only would time and money be thus saved, but the real 

 merits of the proposed work would be brought forward more honestly, 

 or if it had not these pretensions and that recommendation, it would 

 lose a false bolster and fall. It is well known that the skill and science 

 of the different Engineers is frequently useless to them, with all their 

 assured knowledge, by their failure as witnesses. Thus George Ste- 

 phenson is never put into a witness-box, if his friends can keep him 

 out, he has not the temper for cross-examination by persons he consi- 

 ders ignorant of the subject, and with his opinion of himself, it would 

 be impossible to find any person he would submit to. No man however 

 deserves more credit than George Stephenson, for the manner he has 

 advanced himself in the world, which is in itself no greater proof of 

 his natural abilities, than his acknowledgment of it, is of his real 

 unaffected excellence of heart — he is however a theorist of the wildest 

 kind, and until he became a coal owner, felt that the first things in the 

 world were railways and the first person George Stephenson. He has, 

 notwithstanding his energy and knowledge of coals, failed to intro- 

 duce them into public use at a rednction in their price, as he promised 

 lie would, and no inland coal will do so, however much its introduc- 

 tion into the metropolis may interfere with the sea-born supply. His 

 railways are not always the best or most profitable, and we think he 

 has made a mistake also in becoming chairman of any railway com- 

 pany. Robert Stephenson, with a higher education is more calm and 

 self-possessed and makes a better witness. Walker, sharp, quick 

 and clever, may always be relied upon for all he undertakes. Sir 

 John Rennie, however, possessed of all the knowledge on the subject, 

 cannot stand the badgering of counsel and forgets his professional 

 service in his gentlemanly feelings. George Rennie is too retired 

 and modest to make known his extensive information and much 

 mechanical knowledge under the ordinary examination of counsel — be 

 must be drawn out, and thus makes an honest, conscientious, and intel- 

 ligent witness. Young Brunei is clever and self-possessed, and would 

 not be easily put down. Locke's testimony would look hard, matter-of- 

 fact, and solid — economical in all its parts. Giles is hasty, anxious, 

 but determined not to be put down ; Cubitt, quiet, calm,' and firm. 

 Vignolles, energetic and fiery, looking the very personification of 

 some new and wild theory, to be put into immediate practice by his 

 instrumentality, would rather astonish his audience by his bold expos- 

 tulations and warm support of them, than convince by his arguments 

 and facts, except in matters of detailed and minute expense in practical 

 experience — his evidence has, however, been largely counted on by 

 his employers. Braithwaite is a clever machinist, with an inquiring 

 mind ; and, in our opinion, has been spoilt by being made a railway 

 engineer; in this latter position his only experience is the Eastern 

 Counties line, and his declaration of the' correctness of his original 

 estimates for the whole line to Yarmouth, made at a public meeting a 

 year and a half after obtaining the act, will hardly add to the 

 confidence of the public in his future undertakings ; his self- 

 opinion and readiness will always support him, whether as a witness 

 or advocate. Bidder is, perhaps, the most perfect witness; for 

 though Rastrick has the hardest mouth of any, and the most impur- 

 turable determination not to be beaten — yet Bidder, with all the same 

 pertinacity has, in addition, an effrontery of manner (however unin- 

 tentional; which defies the most resolute opposition ; Gibbs is honest 

 and straightforward, and having bought his experience on estimates 

 somewhat dearly on the Croydon, would never again deceive himself, 

 or others." 



Ytar Book of Fuels. London : Tilt and Bogue. 184-3. 

 This very useful annual abounds with a store of information ex- 

 tracted from numerous scientific periodicals and daily papersof the past 

 year, and which exhibits the progress of science during that period. 



A Hand Book for Plain and Ornamental Mapping and Engineering 

 Drawing. By Benjamin P. Wilme, C.E. Part IV. 



This part, like the previous numbers, contains some useful exam- 

 ples for reference; among others are sections of stratified rocks, 

 titles for maps and designs, Gothic letters, &c. 



NOTES ON STEAM NAVIGATION. 



Slide halves. — As the formulae we gave on a former occasion in 

 reference to the effect of any particular quantity of lap on slide valves, 

 have not, we understand, been thoroughly uaderstood by the less 

 scientific portion of our readers, it may be useful to reduce them to 

 the form of common arithmetical rules. 



To find at what part of the stroke the steam is cut of. 



Rule. — Divide the cover on the steam side by half the stroke of 

 the valve. Find by a table of natural sines the arc whose sine is 

 equal to the quotient. Take the double of the arc thus found and 

 subtract it from 90°. Find (in the same table) the sine of the re- 

 mainder; add 1 to the sine thus found, and multiply the sum by half 

 the stroke of the piston. The product will be the space travelled 

 over by the piston before the steam is cut off. 



To find at what part of the stroke the exhaustion passage is closed. 



Rule. — Add the cover on the steam side to the cover nn the ex- 

 hausting side, and divide the sum by the length of the valve stroke. 

 Find the arc whose sine is equal to the quotient. Take the double of 

 this arc and subtract it from 90°. Find the sine of the remainder, add 

 one to it, and multiply the sum by half the stroke of the piston. The 

 product is the space passed over by the piston before the exhausting 

 passage is closed. 



To find at nhat pari of the stroke the exhaustion passage is opened. 



Rule. — Subtract the cover on the exhausting side from the cover on 

 the steam side. Divide the remainder by half the length of the 

 valve stroke. Find the arc whose sine is equal to the quotient. Sub- 

 tract this arc from 90°, and find the sine of the remainder. Add 1 to 

 it, and multiply by half the stroke of the piston. The product is the 

 space passed over by the piston before the exhaustion passage opens 

 at the opposite end of the cylinder. 



All dimensions must of course be taken in the same measure, 

 whether feet or inches. If the eccentric be so placed as to make the 

 steam port be considerably opened at the commencement of the 

 stroke, or so as to give a considerable lead as it is termed, the amount 

 of the lead must be added to the cover on the steam side. 



Covering boilers with bricks. — The iron platform above the boi!er on 

 which the coal generally rests, becomes quickly worn away by oxida- 

 tion, and the boiler beneath it is generally much injured from the same 

 cause, the whole top of the boiler being necessarily inaccesible, 

 thereby imposing an insuperable obstacle to painting and even to 

 inspection. To obviate these evils, as well as to prevent the escape 

 of the heat, a covering of bricks set in Roman cement was some years 

 ago applied to the boilers of the steam vessel Tagus, and has been 

 found to accomplish its purpose effectually. Upon this covering of 

 bricks the coals repose —the expence of an iron platform, and what is 

 more important, the expence and inconvenience consequent upon its 

 constant repair have thus been avoided, the shell of the boiler is pre- 

 served from corrosion, the intolerable heat of the coal boxes is 

 obviated, and fuel saved by the conservation of the heat. The expe- 

 pedient is an exceedingly economical one, and we look upon it as 

 effectual and judicious in every respect. 



We have received another letter from Greenock, signed J. G. 

 Laurie, respecting the formula we gave in our Notes on Steam Na- 

 vigation, respecting the heat contained in surcharged steam, and in 

 which our correspondent says, " I again assert, in the face of the de- 

 nial in your last number, that the formula is misapplied." The best 

 mode, perhaps, to refute the alleged misapplication, is to investigate 

 the question by an independent method, in order to see whether the 

 same results are obtained; and should our readers afterwards conclude 

 that the " total misapplication" applies rather to our correspondent's 

 correction than to our original statement, we are at least not respon- 

 sible for the discourteous manner in which the intimation is conveyed. 



(1) When air is heated, it expands, and the increments of volume 

 are proportional to the increments of temperature. Every increment 

 of 1° in temperature produces an increase in volume -^ part of the 

 bulk of the air at 32°. This rule lias been found to apply to steam 

 out of contact with water. — (Thomson on Heat.) 



(2) The specific heat of steam out of contact with water is inversely 

 as its specific gravity, and at 212 and saturated is "847. From these 

 data, the amount of advantage derivable from the use of surcharged 

 steam may be computed. 



