1841.] 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



415 



RAILWAY FRICTION BAND BREAK. 



Sir — The want of a better system of breaks for stopping or retard- 

 ing railway trains, has suggested to my mind a plan which I believe 

 to be new, and calculated to remove some of the defects existing in all 

 those now in use ; should you think the accompanying sketch and 

 description worthy a corner in your useful Journal, I think much good 

 would be done by directing the attention of mechanics to the subject. 

 I need scarcely say that in the arrangements of the levers in the dia- 

 gram, the object in view has been to show the principle clearly, rather 

 Oian to show the best application. 

 I am. Sir, 



Your obedient servant, 



George Spencer, 

 5, Hungerford Street, Strand, Mechanical Draughtsman, 



November, 19, 1841. 



S 



In the construction of all the railway breaks in use, there appears to 

 me to be two radical errors; 1st. The breaks are applied to only a 

 small part of the wheel, and consequently its power is unnecessarily 

 limited. 



2nd. The bearings of the break axles being on the carriages, and 

 the springs intervening between them and the wheel to be acted on, 

 the pressure or friction is never uniform, and the breaksman therefore 

 finds a difficulty in judging the amount of pressure necessary to stop 

 the train. 



Now I think these objections may be obviated, by applying the fric- 

 tion band so commonly used in cranes; on this plan the momentum of 

 the train might be received in any quantity the breaksman might judge 

 proper. 



I think having the break axle bearings on the wheel axles, even 

 with the present breaks would be a great improvement for the same 

 reason. 



The diagram will be readily understood by reading the references 

 in the order of the letters. 



reference. 



a a, friction wheel and band; 6, tightening bar ; clever; li, lever 

 fulcrum ; e, bearing bar on axle shaft g ; //, supporting guides. 



ON THE POWER OF STEAM ENGINES. 



Sir — I am glad to find in your November number one modest advo- 

 cate for the introduction of the Wave principle, yet when a failure 

 does take place, as was the case with the Flambeau, we mnst be frank 

 and admit it, and not clothe it with difference of opinion in calculating 

 the horses power of steam engines. 



If Y. takes the trouble to examine the calculation in my pre- 

 vious communication, he will find the mean pressure on the piston 14 tlj. 

 not 7, 7'1 or 7'3 as he would have it, without any reference to the 

 pressure on the boiler. I should like to know if 7, 7-1 or 7-3 would 

 hold good in the Cornish engines. 



Again, I would ask if an engine made 27 strokes of 5 feet would 



that amount to 220 feet of piston? I think not; 270 feet will be 

 about if, and Y. will find I only grant greatest speed on the Cyde at 

 this rate. 



Again, I have no objections to Y. using 33,000 for his divisor' 

 deducting 25 per cent, on 44,000 I think he will find little difference. 



Again, " the least steam assertion is granted, by the account of the 

 change of the boiler." I would ask again, would the Cornish boilers 

 supply steam the whole length of stroke? "but the effect of a new 

 and probably heavier boiler is curious, and an accurate statement of 

 the facts would be valuable." Y. might have omitted "probably'i 

 altogether, every one knows if more steam is wanted, more heating 

 surface must be given, consequently the boiler must be heavier, and 

 the effect of course greater draught of water, and I think Mr. Scott 

 Russell must have known this before he made the proposal. I think 

 Y. will find from this enough to convince him that the assertions made 

 in page 312 is not "based in any degree on the unsound foundation 

 of the difference stated." 



I remain. Sir, 



Your obedient servant. 



H 



November 12, 1841. 



REVICW^S. 



Heath's Picturesque Annual for 1842. Paris in 1841 : by Mrs. Gore. 



Although some of them are not particularly fresh — rather the re- 

 verse — the architectural subjects contained in this new volume, are 

 ably treated in themselves, being from the pencil of Allom, one of the 

 first architectural draughtsmen of the day. It will, perhaps, be thought 

 that Paris itself is now rather an exhausted subject, and that there is 

 very little to be found but what has in some shape or other been ex- 

 hibited to the public. This, however, is so far from being the case 

 that we could mention several buildings, which we expected to find 

 here illustrated for the first time, but which seem to have quite escaped 

 the artist, notwithstanding that they are of cousiderable importance. 

 Surely the Hotel de Ville, the Ecole des Beaux Arts, with its screen 

 from Chateau Gaillon, the Hotel du Quai d'Orsay, Notre Dame de 

 Lorette, and several structures— some of them still in progress, others 

 recently completed, would have furnished more than the same number 

 of subjects for the pencil. It is not without cause therefore that we 

 feel disappointed at here meeting with many "old acquaintances," 

 and hardly In a new dress, for the buildiugs are shown from nearly the 

 very same point of view as we have before seen them represented in 

 Pugin's Paris and other works. This might have been avoided, and 

 we regret it the more because Mr. Allom's pencil would have been more 

 worthily employed on edifices which are as yet little known, in com- 

 parison with some of those he has selected. We should have thought 

 that he would have confined himself to entirely new subjects, yet as 

 he did not, we are rather surprised he did not give us an interior of 

 the " Pantheon," by way of companion to that of La Madeleine, in 

 order to afford a comparison between them, as delineated and engraved 

 by the same artists. Beautiful as they are, their merits are of very 

 different kinds, and we are almost inclined to declare in favour of La 

 Madeleine, if only on account of being more novel in character. Its 

 plan is exceedingly simple, forming merely a nave or single vaulted 

 hall, without transept or even aisles, but divided into three compart- 

 ments, each of which is covered by pendentives and a segmental dome. 

 There is besides a spacious semicircular tribune or apsis at the north 

 end, raised a few feet above the rest of the floor, and covered by a 

 semidome. In one respect this interior is distinguished from almost 

 every other of its kind, namely, in being lighted entirely from above, 

 through the centre of each dome ; yet though there are only four aper- 

 tures of the kii;d, including that over the tribune, the church is found 

 to be sufficiently well lighted, while the eflVct is incomparably supe- 

 rior to that produced by side windows ; for great breadth and repose is 

 thus given to the architecture, whereas the other mode occasions a con- 

 fused spottiness. Greatly do we wish therefore that some of our own 

 architects would venture upon the innovation of lighting a church from 

 its roof alone, and getting rid of side windows altogether, more espe- 

 cially as so far from being ornamental they are made invariably the 

 reverse, with exceedingly mean-looking small panes of very ordinary 

 glass, and when ground glass is used the effect is precisely that of a 

 dense fog. 



As Mrs. Gore does not trouble her readers with such dry matters as 

 the dimensions of buildings, or in fact with any thing amounting to 

 description of them, we may as well inform ours that those of the in- 

 terior of La Madeleine are 260 feet iu length by 52 in breadth. The 



