1845^1 



THE CIVIL ENGTXEER AND ARCHITECT'S JOURNAL. 



*335 



grafiogs and books, requires notliiog deserving the name of study or exer- 

 cise of mind, — by adopting such system, arcliitccts virtually renounce both 

 the name and privilege of artists, at least as far as the Orders are concerned. 

 If only correctness is to be aimed at, one man's Doric or Ionic is just as 

 Rood as another's. Those who have talent and geiutic taste of their own, 

 forbear to exercise it ; and those who have none, tan nevertheless exhibit 

 to us most unexceptionable columns so long as they have nothing to do but 

 merely lake what they find ready provided for all alike. To be sure the 

 " correct" people of the latter class do frequently betray themselves very 

 egregiously, since they are apt to put on the "lion's hide" of classiiality 

 in such a blundering manner that the cars, and not the ears only, but a 

 great deal more of the real animal that is so disguised, is plainly per- 

 ceivable. 



V. In speaking of Cotlage Architecture, Gvrilt has told us that it re- 

 quires the minimum of mind, but he forgot to inform us how much mind, 

 and what degree of nous, are required for slicking up a row of columns in 

 front of a building, as is frequently done where, so far from there being 

 anything in the building itself to warrant them, either on the score of 

 utility or of decoration, they are in positive contradiction to its character, 

 utterly at variance with its style in all respects, merely show total igno- 

 rance of composition, and cause the opposite extremes of taste to appear 

 jumbled up together. Instead of being admired for their porticoes, pro- 

 ductions of that stamp would not even have been tolerated, had the public 

 been but as capable of judging of architecture as they are of the other fine 

 arts, music included. So far there may be policy in keeping, or endea- 

 vouring to keep, the public in their present ignorance of architecture, — in 

 scaring them away from the study of it by mystifying it as much as possi- 

 ble, and by ridiculing the very notion of their attempting to become ac- 

 quainted with it. Still the policy is as short sighted as it is ungenerous, — 

 injurious also to the interests of the art itself, since it is, of all of them, the 

 one which is most dependent on and most at the mercy of public taste, and 

 must flourish or decline accordingly as that taste happens to be good or 

 bad, intelligent or the reverse. There is, besides, this peculiar disadvan- 

 tage attending the induenceof bad taste in architecture, namely, that after it 

 has ceased, and a better one come up in its stead, the unlucky productions 

 of the former ill-fated period remain to disgrace us, and after having been 

 fgnorantly admired in their day, to excite derision, contempt and disgust. 

 For be they crer so paltry as architecture, buildings — more especially such 

 as are intended for durability — cannot be got rid of, nor shut out of sight 

 at pleasure. We cannot aflord to pull them down because they are eye- 

 sores, nor is it always that propitious Vulcan will come in the shape of a 

 conflagration and sweep them away, as he did Wyatt's Gothic House of 

 Lords. Instead of reproaching Nash for building in " lath and plaster," 

 we ought rather to feel obliged to him for not having perpetrated his 

 wretched designs and " monstrosities" in more durable materials, inflicting 

 them upon posterity as well as upon the contemporary generation. After 

 all, the public are the real arbiters of the fate of architecture, though it is 

 a truth which architects themselves do not, or it may rather be suspected 

 trilt not, see. Taking their motto from Horace, they say with him, " Odi 

 pro/anum vulgus, et arceo." They seem to be of opinion that the more 

 ignorant the public, all the better for them ; and so, indeed, it may be — 

 well for them, yet deplorable enough for the Art. 



ATMOSPHERIC TRACTION. 

 By F. S. Haydon, B.A., Jesus College, Cambridge. 

 Inteatigation of Power Lost by the Preliminary Exhaustion. 

 It is proposed in this paper to investigate the relation which subsists 

 between the power expended and the useful effect obtained on an Atmo- 

 spheric Railway, in which the dimensions of the exhausting and working 

 apparatus and the working pressure in the train piston are known, the 

 effects of friction and leakage being omitted. 



The construction of these railways is so well known that any description 

 of the machinery used to produce motion would be superfluous. 



The diagram represents the air-pump and part of the branch-pipe con- 

 Becting the top and bottom of the barrel of the pump with the main. 



A B is the barrel of the air-pump ; C, F valves opening outwards ; 



D, E valves opening inwards. Let 

 A 15 = a, A M=J-, area of piston 

 M = A, A = capacity of air-pump, 

 IS = capacity of branch-pipe, C = 

 capacity of main, density of atmo- 

 sphere = p. 



Then, by known principles, the 

 density of the air in the main after 

 n strokes of the pump, will equul 



(B + C \ H „„ 



aTiTTc; "P^KV^uppose. 

 The piston is supposed to be per- 

 forming its «ili stroke. Let II be 

 that point in its path at »hich the 

 valve C opens, and let A II = i ; we 

 have (since in order to open the 

 valve the density of the air between 

 JE* II and A must be greater than that 



of the atmosphere). 



Density at (n- l)th stroke : density in A H : : 11 "~ ' p : p : : R "- " : 1. 

 But ttiese two densities are in ratio of A II : A B. 



.•.« = Il''-'o (1) 



Next, to determine the pressure of the air on both sides of M, we have — 

 I'ress. of air in A M : press, of air in A U ( = press. of atmosph.) : : A 11 : 

 AM-.:4:.i ::U"-' a:.,- by (1) 



R "" ' 

 .•. Pressure against M= x ix 15 lb. (2) 



Again, the air which flows in from the main filled at the beginning of the 

 stroke a volume li -H C ; in the present position of the piston it fills a volume 



15 + C -h A , therefore 



Pressure of air fro 

 at end of (n— l)th stroke 



main when piston is at M : pressure of air in main 

 B-i-C : B-t^C + A^^^. 



■. Pressure in direction of M's motion = R' 



= 15 *R"-' (S-A)> 



(3) 



Putting A + B -I- C = S for shortness. 



The first of these two pressures continually increases until T = i, when it 

 becomes equal to the pressure of the atmosphere ; after this it remains con- 

 stant. The second diminishes continually throughout the whole extent of 

 the stroke. 



The tcork done in the nth stroke will be obtained by integrating the ex- 

 prossions (2) and (S), tlie first from x = a to a=4, the second from a- = a to 

 ,! =0, subtracting the second integral from the first and adding to the result 

 the product 



15 *x« = 15R''-' ak 

 corresponding to the constant pressure against M after the opening of the 

 valve C. Thus we have, if W^^ represent the work done in the nth stroke, 



V /* dx S-A /"'^i^-—)} 



w^^uR'.-.a.jwy -.— y -^-^( 



= 15 R' 



ai\ l-(n_l) log H + 



1 S-Al 



Giving (n) the values 1, 2, 3, &c. up to n in this expression, and adding 

 the results, we find for the whole work done in n strokes, remembering that 

 S-A " 



— r — =R, the expression 



15ai/^l-HR + R^ + ... + R«-'') /'i+^_J^,„gR'\ 

 _ Al + 2R^-. ...n~^R«-'\ logRJ 



-(»'o^-<^^#-")'-«) '.. 



To tiike an example — suppjse the ru.uerical vaines those of the Dalkcv 

 Railway, namely — 



43J* 



