1848.] 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL 



327 



thrust out of sight, it is not greatly to he wondered at if many 

 are deterred from sending anything at all. To such, other oppor- 

 tunity of exhibiting would be welcome ; and their contributions 

 would, it may be presumed, be equally welcome and serviceable to 

 the "Association. Without support of the kind from otliers, and 

 the extended interest so created for the success of the undertaking, 

 there might not be attraction sufficient to produce extraction — to 

 wit, of shillings from the pockets of the lieges. We speak merely 

 upon our own conjecture, but take for granted that the exhibition 

 in question would require the usual shilling passport for admission 

 to it ; because otherwise, the public would be excluded, and the 

 exhibition be merely a private one, open only to the members and 

 their friends, so that any good result as to diffusing a taste for 

 architecture as a branch of design would be frustrated. 



What renders it so highly desirable that a special exhibition of 

 architectural drawings and models of every class should be estab- 

 lished is, that productions of the kind have no chance of ob- 

 taining any attention so long as paintings are to be seen at the 

 same place. It would be almost unreasonable to expect that they 

 should, especially at the Academy, where the pictures are so nu- 

 merous that they alone afford quite occupation enough for several 

 visits. There, the architectural subjects are scarcely looked at at 

 all, except just by those who make them their chief object. Let it 

 then be fairly tried, whether, when withdrawn from its eclipse 

 at the Academy, and allowed to display itself in a different orbit, 

 it has really no power of attraction for the many — we do not mean 

 the mob, but those (and they are many) who, if they possess not, 

 affect at least to have a taste for art generally. 



Supposing that the "Association" now intend to bestir them- 

 selves in good earnest, one thing which they ought especially 

 to consider beforehand is, that architectural drawings require pro- 

 portionably a much greater space for exhibiting them than pictures 

 of the usual kind do, — because they require to be inspected as 

 closely as miniatures or engravings ; consequently, little more than 

 the direct line of wall on the level of the eye can be made avail- 

 able for the purpose. It is of no use — rather a mere mockery — to 

 profess, as the Academy does, to exhibit productions of the kind, 

 and then hang the majority of them where it is only by great 

 effort that their subjects can be made out, and all detail is com- 

 pletely lost. Mr. Billings — who, by-the-by, at the opening meet- 

 ing of the present season, signified the Association's intention to 

 get up the exhibition in question, — observed that he himself had 

 no right perhaps to grumble at the Academy, because, of eight 

 drawings which he sent in this year, seven were hung up — but four 

 near the ceiling, and three near the floor. Considering how many 

 subjects of his were admitted, he had reason to look upon himself 

 as highly favoured — if it be any favour or compliment at all to 

 have drawings received merely because their frames happen to be 

 just the size to fit in " very nicely" with others on the same part of 

 the wall. Such must ever be the consequence of the abominable 

 dove-tailing system in hanging pictures and drawings, which fre- 

 quently renders it necessary to put a good subject or production 

 in an unfavourable situation, or else an inferior one in a good 

 situation, merely because no other places where they would so well 

 fit in can be found for them. Possibly, however, our advice may 

 he altogether superfluous, since it is possible that the purposed 

 exhibition will turn out to have been a mere flash in the pan. 



the condition y := x must be satisfied ; and for no other point can 

 it be satisfied. This point c' must be found by repeated trials. 



ON A READY METHOD OF DETERMINING THE 



WIDTHS OF LAND REQUIRED FOR THE 



FORMATION OF A RAILWAY. 



We will suppose the centre line to be staked out, and the dis- 

 tance from the top of the peg to the intersection of the slopes to 

 he given. Let A be a centre-stake, at which the half-widths are 

 to be determined ; B, the intersection of the slopes produced ; and 

 rto 1, their ratio. The level must be placed at some point D, and 

 the line of collimation adjusted so as to describe a horizontal plane 

 at a distance a B above the point B (fig. 1), for a cutting. B A = 

 K; A a = A; e c' =; a c := A', the reading of the staff when stationed 

 at c'. Then we have, 



Bc = Bo — ac = BA-(-Aa — ac=K4-A — A', and the 

 length of the horizontal line through c' = cc' = a:'=::rX Bc = 



r{K + h — h') = r{K + h) — rh' = aa' — rh' (I) 



The horizontal distance of c' from a B, must also he measured with 

 the chain, and this we will suppose to be y. It is evident, that at 

 the point c', where the slope B o' meets the surface of the ground, 



Fig. 1,— Cutting. 



In the case of an embankment (fig. 2), 



JT = r X B c = r{K — h + h') — r (K - A) + r 7.' = 



rBa-|-j-ft' := a(^ \ rK (2) 



Hence, whether there be cutting or embankment, we must deter- 

 mine the half- width (aa^ at the level of the line of collimation ; and 

 in making repeated trials, we have nothing more to do than multi- 

 ply the reading of the level-staff (/*') for the slope by )•, and add 

 the product to a a' for embankments, or subtract it for cuttings, to 

 obtain the value of x, which must be compared with the horizontal 

 distance (i/), found by measurement with the chain. Repeated 

 trials must be made until a point is discovered which satisfies the 

 condition y ■= w. 



Fig. 2. — Embankment. 



Take, as an example, fig. 1, which is a cutting. 



B A = K = 26-2 ft. ; A = 2-13 ; >• = 1^ ; 



aa'=rxBa = r(K + A) = 1^(26-2 -f 213) = 42-5; 



let the staff be held at /', and suppose the reading to be 6'S = A' ; 



thenrA' = 9-75; and j? =//" = aa' — rh' — 42-5 — 9-75 = 32-75. 



By measurement with the chain, y is found = 22-00 ; 



.-. y is not equal to x. 



Again, suppose the reading c'e of the staff ate' to be 10-7 = A' ; 



then r A' = 16-05; and x — 42-5 — r h' 



= 42-5 — 16-05 = 26-45 "> 

 and y is found by measurement to he 26-45/ 

 .•. y z= X ; and c' is the point sought. 

 Example of an Embankment. — Slopes 1| to 1. Let K = 42-36 ; 

 A = 2-43. Then (K — A) = B a = 42-36 — 2-43 = 39-93 ; 

 and aa' = rx B a = 1^ X 30-93 = 59-9. 

 Suppose the reading c' e of the staff at c' to be 10-05 = A', 

 then rh' = 15-07 ; 

 X =z aa' + rh' = 590 + rh' = 59-9 -|- 15-07 = 74-97 \ 

 and suppose that y, found by measurement, is ;= 74-97 J 



then c' will be the required point. 

 These necessary calculations are very simple, but they are also 

 very numerous, and I have found it advisable to substitute a kind 

 of sliding rule, which at once performs the multiplication of r and 

 A', and adds the product to, or subtracts it from, a a'. {Het 

 figs. 3 and 4.) 



