2 ~0 2~ fec~an ics a ~ d C/zem, is l~ , j .

touched; and, if~ instead of the half seetiorl of boiler above. A~ I), a strong bar were placed l,arallel with, and at at small distance frorn the solid body, A, 1), connected to it at each end, by a flexible malerial , lhe so[utiol:l o[" the.3 pa r [h i t [bree at, ]), wotlld, still hold, by a slight variat ion i~ lhe defi.tfitio~ o{" terms.

Witl~ the half seetio~ attached, as above, to the solid body, the operat ive fbree to rupture ~t I), would, on both theories, be as the semi- d iameter ; and,at]{ , by the r t :ceivedtheory,as the semia 'adius: whereas , I contend, tha.t the solid bodv~ below iX, I:~ has ltot ell'coted t:.tly~ ch4~b~e. ,-, ia tile conditiol*s of ~hc poim, B, which would receive a strain to part horiz{mta~ly, cqtml to the quarter circle.

Should, what I lmvc :5tzttt:d~ or may state, on this subject, be thought o[ sutIici<mt imp.orial~m to imhtt:e ~. trial by e:xpedment, a serai-ch'eh~ of a :flexibi,,~ material , as l~el'e represet/ted, a t tached to a. solid t)ody, would he tlm :simplest ~H~:tt~o4, a.m[ lbrm the strougest contrast i~ test- lug tile two thcoric~; fbr, at B, tim ditl'crenee would be as 1 to .3.14 i or, by the received rub , the semi-circle would uuifbrmly part at A, or B, and by nm~o, at B.

CiJ~cin~a&', sore g~d/ / , 18t 3. Ell'RATA.

['age 102--20th line, tbr "~{reat~.r," w'ad "¢,'~arter."

~ ~ " ~ " dircctto,s in um:~" read '~ dlr~cl/o~# ; to 5e reaisled {r~ on~?." " 104--20th " "/){tr.su~tdc<l," read "})ersuadcd/'

.EgU)e~.i,me~l.r o~, t k e ew)/o.; ' /ve / b r c e o f O<v,q.<..~ a ~ d 147&A{;e~z gu.ve.< l~y .I a x,{:s ;1 o:~:as'ro:x, Esu..

h~ 1841. I took out '~t patent [or obtainit~g motive power from the explosive, a.l~d eoudei(sing propert ies of oxygen, and bydroae~ gases, h~ order to asccrt'aitl the power . and length of" stroke w}{]ch those gase.s would give when exploded in a cylinder~ I commenced, on the ~":lth ' ' % oi • prit, 1841, 8. set. of' experiments~ of which I now give the results.

Tim apparat t is \vitl~ which I made the exper iments , consisted of a s troug ca.stdro~ cs,[inder , accurately bored, so that ils d iameter was exact ly two i~ches and thirteet>sixteenths of an inch. This d iameter gives a sudhce on the piston o[' six square inches.

The piston was fitted very accurately into the cylinder. I have ascertained it to work perfectly air-tight. On the top of' the piston, t,here is a cross-head, and spind/% fbr placing weights upon. The ends of the erossdmad w o r k in east-iron guides.

The gases are admitted to the cylinder by stop-eoeks~ a~d are ex- ploded by aI~ electric Sl)~.tl'l{.

I shall uow describe the prel iminary a r rangements made befbre mak ing each e.xperimc~it.

[ ascertained the weight o[' lhe piston, pistor>rod~ and other appen- dages, which !he gases mtt>:t move when the piston is put in motiotb to be 9 lbs. 5 oz.

I then ascertai~ed, that; to overcome the fl-iction o f the piston, i~ required 5 [bs. 1 oz. , together with its o w n we ight ; therefore, add 5