THE 



CANADIAN 



NATURALIST AND GEOLOGIST. 



Vol. Vir. AUGUST, 1862. No. 4. 



ARTICLE XXn.— ^ Lecture on Force, delivered before the 

 Royal Institution of Great Britain on the 'fith of June, 

 1862, hy Prof. John Tyndal, F.R.S.* 



The existence of the International Exhibition suggested to our 

 Honorary Secretary the idea of demoting the Friday evenings 

 after Easter of the present year to discourses on the various agen- 

 cies on which the material strength of England is based. He 

 wished to make iron, coal, cotton, and kindred matters, the sub- 

 jects of these discourses ; opening the series by a discourse on the 

 Great Exhibition itself ; and he wished me to finish the series by 

 a discourse on Force in general. For some months I thought 

 over the subject at intervals, and had devised a plan of dealing 

 with it ; but three weeks ago I was induced to swerve from this 

 plan for reasons which shall be made known towards the conclu- 

 sion of the discourse. 



We all have ideas more or less distinct regarding force ; we 

 know in a general way what muscular force means, and each of 

 us would less willingly accept a blow from a pugilist than have 

 his ears boxed by a lady. But these general ideas are not now 

 sufficient for us ; we must learn how to express numerically the 

 exact mechanical value of the two blows ; this is the first point 

 to be cleared up. 



* From the L. E. and D. Philosophical Magazine for July, 1862. 

 Can. Nat. 16 Vol. 711 



