1839.] 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



371 



of the stroke of the pistons wiU be as the length of these lines indi- 

 vidually, thus involving an expense of steam in the Concentric engine, 

 equal to the advantage which would seem to arise from the use of it. 



Another view of the case may be taken, somewhat simpler than the 

 foregoing, by which it may be shown that the mode of couni\unicating 

 power by the Concentric engine is a matter of every day occurrence. 



Let the lever M represent one lialf of the beam of an ordinary beam 

 steam engine, B its connecting rod working the crank C ; these toge- 

 ther delineate movements almost inseparable from the use of the 

 crank, and nearly coeval with the steam engine itself, as it came from 

 the hands of its great improver ; the parallel motion alone is wanting 

 to till up the picture : and if it is to this circumstance, that the supe- 

 riority of the Concentric engine is to be attributed, I fear its days are 

 numbered as an engine "by which great power is gained;" that it 

 may take its place with many of the best locomotive engines now in 

 use, is not to be denied : but I beg respectfully to protest against the 

 possibility of its exerting more force than others from the same 

 quantity of steam. 



It is under these impressions, that I have ventured to address you, 

 and in the belief that these imperfect observations will account for the 

 different results, obtained from the experiments made on the two 

 engines; I am also inclined to believe that their appearance in the 

 Journal, would be useful in counteracting whatever erroneous views 

 may have been formed by the perusal of the tables. 



1 am, Sir, with great resjiect, 

 Vour obedient servant, 



Canon, Augitsl IGM, 1S3P. Ji.>hx Mac Do.\.\ld. 



CURVES ON RAILWAYS. 



Sir — I lieg to forward to you the following remarks on a jjoint 

 wliich has not been noticed in any of the numeroiis essays on this sub- 

 ject which have appeared in your Journal. 



It is one of considerable importance, and is not (that I am aware of) 

 to be found in print, except in Fambour's work on locomotive engines; 

 the formula there given produces the same practical result as that 

 which I have deduced, but is, I think, somewhat less simple in its 

 application. 



Your's respectfully, 

 M. 



How much must the outer rail of a curve be raised abo\ e the inner, 

 in order to coimteract the centrifugal force of a carriage? 



Let A be the centre of gravity of the carriage ; draw a vertical line 

 A B, and a horizontal line A C, representing the weight and centri- 

 fugal force respectively ; then A D, the diagonal of the rectangle, will 

 be the resultant force of the tvvo. 



~:::;:i».l" 



Now If a line (E F) be drawn at right ungles to A D ; and D E, D F, 

 be taken upon it each equal to half the distance between the rails, the 

 force A D, being perpendicular to the line of support, has no tendency 

 to press the Hange of the w heel against either of the rails E or F'. 

 This position of the rails, therefore, will answer the conditions of the 

 problenii 



Draw F H horizontal, and E H vcrticd. 

 Let W = w eight of the carriage. 

 W / := the centrifugal force. 

 R = radius of curve in chains. 

 V = velocity in miles per hour. 

 r :^ radius of curve in feet. 



V = velocity in feet per second. 



g = It5-ri7- 

 E F ^= « in feet. 

 E H = .1- in feet. 



W !>'-' 

 Then the centrifugal force = - — - (see any work on Mechanics,) 



■ -^ 2 gr •■> 



XlO^X6(3R=?X-'^"^'^'=^-^- 



By the similar triangles A B D, F H E, 



A B : B D : : F H : E H 



or w : W/ : : Va' — .r* : x 



■'. 1 : /■■ : : a- — .v- : .v-. 

 •■• 1 +/' :/=::«=: x-^ 

 .■.x = -^tL^ 



Kxampje. — What must the elevation be for a curve of GU chains, 

 (39GU fee't), radius and velocity of 30 miles an hoar, (44 feet per 

 second,) the distance between the rails being 4-75 feet? 



M«-/=2^riGSWo = -"'^-' ^"■^' Vr+7^=1-"0011; 



4*7.5 X *01.52 



.'. .r = — '- — ^ = ■0722 =; •SGG4 of an inch. 



The above formula is extremely simple, as the value of j/ 1 +_/'- 

 will be very nearly 1 in almost all practical cases. 



ON WARMING OF BUILDINGS. 



Siii — Upon reading your remarks upon the warming apparatus at 

 Mr. Babbage's house, described in my pamphlet, I find you consider 

 that the part which is not effective is owing to the malformation of 

 those pipes which branch from the multiple cock ; ;\s this is not by 

 any means the case, you will perhaps have the kindness to notice the 

 following few remarks in explanation. Mr. Babbage confined his ex- 

 periments to a certain small amount of fuel, working his apparatus at 

 the low heat of 250" Fahr., this was not sufficient to cause a quick 

 circulation through the whole extent of pipe, the four difftrent courses 

 containing 890 feet. 



The furnace being placed in one of the servants' sleeping rooms, it 

 was more important to keep this room cool than to w'arm the rooms 

 in the upper part of the house. 



Mr. Babbage succeeded in his two principal objects, 1st, the making 

 use of every particle of heat that was practicable, sufficiently with 

 creating a draft in the chimney. 2nd, The perfect self action or re- 

 gulation of the aj)paratus. It is his intention to extend his experi- 

 ments next year, in order to obtain (withuiit producing any additional 

 hat in the furnact room) with a greater amount of fuel, increased 

 effect in the bedroom circulations. 



I remain, Sir, your most obedient servant, 



C. J. Richardson. 



24, Manchester Street, Sept. 10, 1839. 



*** Notwithstanding Mr. Richardson's remarks, we are still of the 

 same opinion, that " it would be far better if the connection of the 

 branches were made with curves instead of at right angles;" if Mr. R. 

 will consult any hydraulic engineer, we have no doubt but what he will 

 have the same feeling on the subject. — Editor. 



Mechanical Brick Making. — At the meeting of tlie British Associatiou 

 at liirniingham, Mr. Cotlani exhibited a model of a brick and tilc-inaking 

 inaclii)ic invented liy tlic Mari|nis of Tweeddale, by which it was stated oO 

 liiicks a niinntc, or nearly .'!0,(l(in liricks a day, might he made, wliilst a good 

 inonldcr could only mould tVoin ,')((1)() to 8000 a day. The clay was put into 

 the niacliinc at one end, and i).issing hctwcen two I'ollcrs was rolfcd into a 

 long l)ar, wliich was cnl intii the rccjnircd length of tlic liricks fiy a cutter 

 ANorkcd by the same \\hccl-^\ork. The l)ricks, on coming out at the opposite 

 side of the machine, were carried h) it to a distance of 2t)0 yards, thereby 

 saving a great amount of time and money in earning, an operation usually 

 ])Crfornic<l by l)oys and women. .Vs a proof of flic superiority of the macliinc- 

 nuule lirick, it weighed 8] Itis., \vhilc a common brick weighed oidy Gij lbs., 

 and the machine-made brick cairied eight times the weight which the com- 

 mon brick woidd sustain. 



