534 FOURTH REPORT 1834. 



Miles per Hour. Feet per Second. Amount of Emersion. 



5 7-30 -1140625 



6 8-76 -1368750 



7 10-22 -1.596875 



8 11-68 1825000 



9 13-14 -2053125 



10 14-60 -2281250 



11 16-06 -2509375 



12 17-52 ........ -2737500 



13 18-98 -2965625 



14 20-44 -3193750 



15 21-91 -3421875 



20 29-20 -4562500 



25 36-50 -5703125 



30 43-80 -6843750 



35 51-10 -7984375 



40 58-40 -9125000 



41 59-86 -9353125 



42 61-32 -9581250 



43 62-78 -9809375 



43-859 64 1-0000000 



On the Collision of imperfectly Elastic Bodies. By Eaton 

 HoDGKiNSON, Salford, Manchester. 



The theory of imperfect elasticity of which Newton gave 

 the elements, from experiments alluded to in the Principia 

 (scholium to the laws of motion), has not always been received 

 with that cordiality which attaches to scientific deductions 

 clearly proved ; and among our neighbours the French, it is 

 seldom used. This circumstance, together with the remarks 

 in a work of great value by a member of the University of 

 Cambridge*, and a suggestion of its distinguished author, 

 made me desirous to repeat the experiments of Newton ; and 

 to seek for data necessary to supply, amongst other things, 

 the laws that regulate the elasticities after collision in bodies 

 of the same, and of different natures. 



In this research I have been, as on former occasions, gra- 

 tuitously supplied with every requisite, so far as I fovnid it ne- 

 cessary, by Mr. Fairbairn, engineer, of Manchester. 



To obtain the results, the mode I usually adopted was nearly 

 that used by Sir Isaac Newton himself, in which two balls. A, 

 B, were suspended from points C, D, with equal radii, so as 

 just to be in contact when hanging vertically ; and the curves 

 A EH, BFG, were circular arcs round the centres C, D, in- 

 scribed on a wall contiguous. The arcs were divided accord- 



* Ml-. Whcwell, in his Mechanics. 



