THE CIVIL ENGINEER AND ARCHITECT'S JOURNTAL. 



[Febbuaby, 



IMPROVED STEAM-VALVE. 



Reghtprrd by Mr. Jostah Evans, of HuydocU Colliery, near 

 Warrington, Engineer. 



Fig. 3. 



area of the lid of the valve at H, and tlie area of the lid of the 

 valve at A, or in such other ])roiiortiiin. By this arrangement, 

 whon nsed as a safety-valve, and wlien tlie dirtercnoe is only one 

 ini-h in area, and the steam at a pressure of 60 lb. per square' inch, 

 the actual weif^'ht to be susi)ended to the rod D will be only 60 lb.; 

 or when used for the working valves of a steam-engine without the 

 centre part C, the area of the seatings A and I? can be so jiropor- 

 tioned that only the weight of the valve-lid will have to be lifted. 



J'ig. 1 is a vertical view of one-half of the valve ; fig. 2, a verti- 

 cal section, showing the valve closed ; and tig. 3, a vertical section, 

 showing the valve open. The arrows indicate tlie flow of the 

 steam through the openings when it is admitted into tlie spaces, 

 a, a. 



The object 

 part C^, e<|ii3l 



of the 

 to an 



improvement is to make the area of the centre 

 inch in area more than the difl'erence of the 



ON THE PRINCIPLE OF RAILWAYS. 



(From the Railway Chronicle.) 



Tlie most important step in attaining a sound knowledge of any 

 subject is to obtain a clear view of the ^^ principle" on wliich it is 

 based. 



Railways, in common with all other results of human intelligence 

 and skill, have their A B C, or elementary principles ; and were it 

 not that I am deeply impressed with the conviction that a con- 

 siderable portion of the railway public (both jirofessional and 

 shareholding) reipiire to be brought back again to school for the 

 purpose of learning-the very first lesson on this important subject, 

 I would not have presumed to beg for a corner in your valuable 

 pages, in order that I might have an opportunity of repeating the 

 elementary lesson which, through your indulgence, some four years 

 ago I attempted to give on the ABC of what I term the "princi- 

 ple of railways." But judging from the increasing number and 

 weiyht of those monster rail-crushing, permanent-way-destroying, 

 dividend-absorbing, Brobdignag engines, wliich are now, from 

 morning until iiiglit, making havoc with the 4,000 miles of railway 

 which branch to nearly every part of Great Britain, 1 am fain to 

 repeat my A BC, in the hope that I may make one or two apt 

 scholars, and, peradventure, reclaim some who ought to have 

 known better than to subject good honest wrought-iron rails to a 

 crushing treatment which neither art nor nature ever fitted them 

 to sustain. 



Were any apology required for intruding the subject on the at- 

 tention of your readers, it would be fimnd in the fact, that such is 

 the havoc which these monster engines are making with the rails, 

 that by their "bills of mortality" their longevity is now reduced to 

 under eight years at the very outside, especially on those lines 

 where the traflSc is considerable. 



Now, when we commercialise this fact in its most simple form, and 

 bring the result to a focus in plain £. s. d. upon 4,000 miles of rail 

 "used up" every eight years, to say nothing of the destruction of 

 other porticms of permanent way, and the increased deterioration 

 of the rolling stock pacing over rails in bad condition, we may 

 indeed say, "that's the way the diridcnds go." 



Were this subject gone into and looked at in its proper liglit, all 

 other reforms would sink, on comparison, into insignificance. But 

 as "it is best in all things to begin at the beginning," permit me to 

 mount the desk and hold forth "for a brief while" on my A B C, or 

 principle of railways. 



Lei-son 1. To what circumstance is it we owe the low amount of 

 tractive force requisite to move heavy bodies on a railway .'' 



Anmeer. Simply to the impenetrability or hardness of the sur- 

 faces, namely, of the rail and the wheel. 



Denionalrntion. Let aaa represent a wheel of perfectly hard and 



impenetrahle substance, and let h b 

 re]iresciit a rail of the same mate- 

 rial ; it is evident that the contact 

 of such a wheel witli such a rail 

 will be an absolute jioint, P. It 

 also follows that tlie force required 

 in moving forward the centre or 

 axle, C, will be infinitely small. 



Tliis, then, is not only the prin- 

 ciple, but also the perfection of a 

 railroad — namely, the least possible 

 mutual penetration of the wheel 

 and rail, so as to (under all cir- 

 cumstances) maintain the absolute 

 point-like contact between the wlieel and the rail. 



Now, let us take another e.xample — namel>', the same demonstra- 



