S6S Pj'occedhiff.s o/'the British Association. 



Mechanical Science applied to the Arts. 



The First Meeting wa^ held on Thursday I3th Attgust. 



President Air Kennie. 



Vice-President. — Dr I-ardxer. 



1. Mr Hodgkinsoii of Manchester detailed some experiments 

 in reference to the collision of beams and piles. This commu- 

 nication formed the continuation of a former paper read to the 

 Association. Tlie results were, 1, That when cast-iron beams 

 were brought forcibly in contact with balls of different kinds of 

 melals of equal weights, the deflection was the same in distance, 

 whatever the nature of the metals was. 2, That the impinging 

 masses rebounded after the stroke, through the same distance 

 under similar circumstances. 3, These eflfiects are not in any 

 way dependent on elasticity, but are the same as theory would 

 point out to be the consequence of the collision of bodies desti- 

 tute of elasticity. He mentioned also that wire resisted fracture 

 most effectually, when it was extended by means of sl weight, 

 equivalent to one-third of the weight required to break it. 



2. Mr ]Mallet read a paper on the fracture of bars of cast- 

 iron. ,,/j 7c5:>-;i..,- . 



'6. Mr Ettrick read an account of a compass which, by a pe- 

 culiar contrivance, adjusted the cardinal points so as to corre- 

 spond with the true points in the horizon ; thus obviating the 

 necessity of allowing for the variation. This effect was produced 

 by securing the needle upon the card by moveable clamps, and 

 adjusting it for the magnetic variation of Greenwich, with a con- 

 trivance for altering it in situations where the local variation was 

 different. 



4. Mr Pritchard sliewed an achrnmatic niicroscoj:)e, in which 

 the angular aperture of the object-glasses exceeds any that have 

 hitherto been constructed. It is peculiarly serviceable in exa- 

 mining flax, cotton, silk, &c. 



5. Mr Russell read a paper on tlie solids of least resistance, 

 in reference to steam- vessels, and related experiments which 

 tended to prove that the form of prow best suited to rapid pro- 

 gress through water, v/as a parabolic one. This was disj^utcd 

 L.y Proiessor Mosely and Dr I.ardner. 



