84 ON PENDULUMS, ScC, 



II. 



Remarks on a Paper of Mr. Bosm^ell on invar lahlc Pen^ 

 dulums, Sfc, In a Letter from J. G. 



To Mr. Nicholson. 

 Sir, 



Introduction to Ac., .1 l ^ ^ i^i- 



Remarks on a ""*^^ ^^^ "° ^^^ appear to be averse to the insertion of 



Paper of Mr. any critical observp-tions upon such papers of your Jour- 



BoswcU. j^^i ag may happen to contain any defective inferences, I 



am induced to transmit you the following remarks on a 



paper of Mr. Boswell's, relative to pendulums, published 



in your Number for February 1805, which I have but 



just seen. 



Mr. B. consi- Mr. Boswell commences his paper by observing that 



iude oi'^ho^xts^^^^^^^^^^^ of the bodies submitted to pyrometrical 



submitted to experiments has been very generally neglected, a point 



pyrometrical -^yhich he would insinuate to be of material importance 



cxpermients as . „ . . , „ , ^^ * 



an element of "^ a" considerations of this nature. He then proceeds to 



great import- state the obvious circumstance that bodies are more or 

 * less speedily affected by the temperature of any surround- 



ing medium, according to the proportional number of 

 their particles which are in contact with this medium ; a 

 pircumstance which, as he observes, is dependent on the 

 shape and mass of the given body. From hence he dci* 

 duces the following inferences : 

 irfe7s^t^ra?a^^ '' ^' That the greater the bulk of any body, the less 

 large body ^' will be its mutability of temperature in proportion, 



would be little a and, of course, the less will it alter its degree of ex, 

 changed by the ^, . „ 



atmospjiere. "-pansion." 



" 2. That a large globe, in the first place, or a cylin- 

 ^' der whose height was equal to its diameter, in the next 

 ^' place, or, in the third place, a large cube, would have 

 " its dimensions very little changed by the fluctuations 

 " of atmospherical temperature." 

 ButMr.B.does The above inferences appear to be inadmissible from a 

 not attend to circumstance which Mr. Boswell seems to have over- 

 Son. " looked, viz. the possibility of a partial expansion of the 

 given body, or of the expansion of one part independ- 

 ently of the remainder, Mr. Boswell's inferences recjuir- 

 ing no expansion to take place until each particle has 

 assumed the tempcFftture of the surrounding medium. 



It 



