10 



THE CIVIL ENGINEKR AND ARCHITECTS JOURNAL. 



[January, 



allow the valve to li.ive the lead, and also cause it to move in the pro- 

 per direction, when the engine is working in the direction of P. 



Let us now turn the crank to B. The eccentric will now stand at ir. 

 To cause the piston to work the crank in the direction of L, the eccen- 

 tric rod end must be attached to the lever 8, as before, which will 

 cause it to stand at .r, and consequently cause the valve to be wide 

 open, with the exception of the little variation caused by the lead, ;is 

 I spoke of in fig. 1. To reverse the motion, tliat is, to cause the crank 

 to turn in tlie direction of F, I remove tlie eccentric rod end from x to 

 r, and by this means (the eccentric rod end being properly formed; 

 the lever will be drawn from r to ;;, eonsefjuently the valve will receive 

 the same cliange as it did in fig. 1, by clianging the eccentric rods, 

 when tlie crank was at B. 



By setting the cranks, in figs. 1 and 2, in any two corresponding 

 points of their revolutions, it will be found that, when the eccentric 

 rod in fig. 2, is attached to tlie lever », the valve will be in the same 

 situation as that of fig. 1, when the rod belonging to c is attached to 

 the lever a. And it will also be found that the changing of the two 

 eccentric rods in fig. 1, will effect the same change in the situation of 

 the valve as the removing of the eccentric rod in fig. 2, from the one 

 end to the other. Hence it is evident that one eccentric, with the two 

 levers, arranged in the manner described, will produce the same effect, 

 in every respect, upon the valve, as is now produced with the two 

 eccentrics. 



The distance s r, fig. 2, will depend upon the length of the eccen- 

 tric rod, and the quantity of lead in the eccentric. If the eccentric be 

 required to give a greater quantity of lead than common, it w ill per- 

 haps be advisable to use two bell crank levers instead. But these 

 particulars are of little importance, the principal object to be attended 

 to is to set the ends of these two levers in the proper places. 



I am afraid I am trespassing too far upon your pages, tlierefore I 

 will conclude with a short explanation of a little deviation in this latter 

 arrangement from the former, whicli, before, I did not think worthy of 

 notice. When the crank is at C, fig. 1, either of the eccentric rods 

 may be attached to the lever a, without moving it. But in fig. 2, 

 when the crank is in that same position, it will be found that the 

 eccentric rod cannot be removed from s to r, without making a little 

 alteration in the levers. It would be a waste of time to enter into 

 a minute explanation of this little alteration, which is caused by the 

 vibration of that end of the eccentric rod which is in connection with 

 the eccentric; upon the same principles as the piston is caused to be 

 in the middle of the cylinder when the crank is at B. 



I remain, Sir, your's, very respectfully, 



John Chjirles Peapxe. 



Leedi, Nov. 9, 1840. 



IMPROVEMENT OF THE HYPSOMETER. 



Sir — The ingenious little instrument for taking altitudes, invented 

 by Mr. Sang and described in your last number, cppears to me greatly 

 deficient in one particular, and that is in tlie means of obtaining a level 

 base line on which to conduct operations; the absence of this qualify, 

 indeed, renders it almost useless on uneven ground, and should the 

 base be extended over a space of SU or IdO feet or yards, the difficulty 

 greatly increases ; in this case, to trust to the eye for obtaining a level, 

 would be out of the question; one miglit as well guess the altitude at 

 once, as a quicker and equally correct method of arriving at the desired 

 result; the instrument, tlierefore, if used alone, is rather contracted in 

 its sphere of usefulness, an additional observation with a spirit level 

 being necessary to obtain a near approach to truth. In saying this, 

 my intention is not in any way to detract from the merits of Mr. 

 Sang's invention; on the contrary, I confess myself much taken with 

 it, and on that account have been turning over the scanty resources of 

 a cranium somewhat obtuse, in hopes of finding something tliat might 

 obviate the defects, which appear as such, in my humble opinion. 



I would propose, therefore, the addition 

 of a small milled-lieaded steel bar, an isos- 

 celes triangle in section, on which the instru- 

 ment should be suspended ; balancing itself 

 thus, a base line will be obtained constant in 

 its level; a cross wire over the aperture b 

 will be necessary to complete the line of 

 coUimation. By these simple additions, 

 altitudes may be taken with much greater precision, and tlie instru- 

 ment will also acquire the properties of a level, sufficiently accurate 

 for the purposes of gardening, for draining, or for levelling banks, and 

 may be used generally except where great mathematical nicety is 

 required. 







should you consider this modification, which springs from a dull 

 man's brain, worthy a place in your Journal, it might, bv chance, be 

 turned to good account by some of your more intelligent readers. 

 Lirerpool, ' Azimuth. 



December 9M, 1840. 



REVIE\VS. 



Companion to the Almanac for 1>)41. Knight and Co. 



We are requested to explain in our notice of the present volume of 

 the "Companion," a most singularly unlucky and vexatious accident which 

 has befallen pages 245 and 6, owing to the hurry with which the sheet 

 containing them was made up for press, nor was the mistake dis- 

 covered till it was too late to correct it by a cancel, the larger number 

 of copies having previously been disposed of. Those of our readers, 

 therefore, who may have happened to have already perused the archi- 

 tectural section, must have felt completely mystified by the descriptions 

 of the Reform Club-house and the Corn Exchange, for they are so 

 strangely intermixed and shuffled together, that it is utterly impossible 

 to understand either as now put together by the printer, who has clapped 

 down the saloon of the Club-house in Mark Lane, and vice versa put 

 the newly modelled area of the old Coin Exchange into Mr. Barry's 

 building in Pall Mall — which, it seems has been improved by Mr. 

 Morris and decorated by Bielefeld. Perhaps this last rather startling 

 piece of information may excite the architectural reader's suspicion, 

 and satisfy him that there must be some mistake, although he may 

 probably not be able entirely to unravel it, — or even if he can do so, 

 to account for it — how by any possibility it could have occurred. In 

 a monthly publication such a blunder would have been of much less 

 consequence, because there the opportunity of rectifying it would have 

 soon occurred, whereas a twelvemonth must elapse before the readers 

 generally of the " Companion" can be satisfied that the architectural 

 critic was not actually muzzy when he made his remarks on the two 

 buildings in question. 



The best way of correcting the mistakes will be to quote the jias- 

 sages where they occur. Speaking of the Reform Club-house he says : 

 " We had imagined that the two smaller divisions both in the coffee- 

 room and the drawing-room above it, would be separated from the 

 other compartments into which those rooms are divided, by screens of 



columns, instead of which we now find that there are only attached 



columns at the angles of the projecting piers which form the breaks on 

 the sides of those rooms, &c." Thus it will be seen that the latter por- 

 tion after the in our quotation, and the rest of the article should 



be transposed from page 241! to the preceding one, and be connected 

 with the line ending with " screens of." Which being done, the other 

 blunder rectifies itself, it becoming obvious that the remainder of page 

 245, line 13 from bottom, belongs to the account of the Corn Exchange, 

 where the paragraph now rendered unintelligible would read thus : 

 " Tlie order is an Italian Doric, the columns of which are so disposed 

 as to form a parallelogram on the plan, having five intercolumns on 

 each side, and three at each end, but in the upper part this shape is 

 converted into an oblong octagon, the angles being cut off by the en- 

 tablature being carried from the column next the extreme one to 



the corresponding column of the adjoining side. The attic and ceil- 

 ing follow the plan of the entablature, and the second of them consists 

 entirely of a very deep cove, through which the light is admitted by 

 means of glazed compartments. The centre, however, or what would 

 be the flat portion of the ceiling is neither glazed nor covered in at all, 

 but forms an opening of thirty feet by ten (surmounted by a cornice 

 and balustrade) consequently the shelter from rain is not altogether 

 so complete as it might be." 



Having quoted enough to correct the wholesale error on the part of 

 the printer, by connecting the passages he had dissevered, we now 

 proceed to make some remarks of our own, noting as a curious cir- 

 cumstance the alteration which has lately been made in the old or 

 south area of the Corn Exchange, in order to shelter it from the 

 weather, at the very time that a design has been adopted for the 

 Royal Exchange, with an uncovered area or open cortile, surrounded 

 as formerly by a covered ambulatory, which though protected 

 from rain above, must be partially exposed to that, ami to other 

 inconveniences attending inclement weather — to damp, fog, and wind. 

 We do not mean to say that Mr. Tite's design is at all more objection- 

 able in that respect than were the others ; on the contrary, it is far less 

 so than the generalitv of them, on account of the very great depth, he 

 has given to the colonnades. What strikes us as singular is that the 

 Gresliam Committee should have settled that very important point, 



