PROVISIONAL REPORTS AND NOTICES. 211 



of the square of the distance ; ' and Dove, ' On the Law of Storms.' — These 

 translations were presented to the Committee by Lieut.- Col. Sabine, and as 

 no illustrations were requisite, it has not been necessary to expend any por- 

 tion of the grant placed at the disposal of the Committee. 



Edward Sabine. 



On the Mode of conducting Experiments on the Resistance of Air. 

 By Eaton Hodgkinson, F.R.S. 

 Mr. Hodgkinson said, that, having been honoured by the Association with 

 a request to pursue some experiments on the resistance of the air, he was de- 

 sirous of exhibiting an instrument prepared for making the first series of those 

 experiments. He proposed, in the first instance, to seek for the force of the 

 wind moving at different velocities upon plane surfaces of given dimensions, 

 these surfaces being either perpendicular, or inclined at any angle, to its cur- 

 rent : to determine this, he intended to place the apparatus upon the front of 

 the first carriage of a railway train ; the road along which the train passed 

 having for a short distance poles stuck up, 100 or 200 yards asunder. He 

 would try the experiment only on days when there was no perceptive wind : 

 and then, if the time in seconds taken in passing between two poles be care- 

 fully observed, and the pressure indicated upon the discs (which were of 

 two and of four feet area, both round and square), the resistance per square 

 foot, with a given velocity, would be obtained. He hoped to determine these 

 facts, with various velocities and at different angles of inclination in the discs ; 

 trying the same experiments with both discs at the same time, to ascertain 

 whether the resistance to a square surface and a round one, of equal area, was 

 the same, and that the results might correct each other. The directors of the 

 Manchester and Birmingham Railway had kindly consented, at Mr. Buck's 

 request, to allow him to make these experiments ; and he was indebted to Mr. 

 Fairbairn for the apparatus. This was placed on the table. It consists of two 

 discs of wood (which may be of any form), made inclinable at any angle by 

 means of screws, and having an attached quadrant to measure the angle. To 

 ascertain the force of the wind, one of Salter's balance springs is placed be- 

 hind each disc, attached to the cross piece which connects the two rods of the 

 discs ; and this, it was expected, would indicate the force of the wind at any 

 moment. If other apparatus were found necessary it would be applied. 



Experimental Inquiries on the Strength of Stones and other Materials. 

 By Eaton Hodgkinson, F.R.S. 



After noticing the present state of knowledge on this subject, and the 

 experiments of Barlow, Rennie, and experimentalists on the continent, Mr. 

 Hodgkinson said, he had long felt anxious to ascertain how the three forces 

 — the crushing, the tensile, and the transverse strength — and the position 

 of the neutral line (that separating the extended and compressed fibres 

 in a bent body) — were connected in bodies generally : and his experiments 

 had for several years been directed to discovering facts upon each of these 

 matters, in order to determine the question. His experiments some years 

 ago, made for the British Association, with respect to the values of hot and 

 cold blast iron, had shown that the ratio of the forces of ultimate tension 

 and compression was nearly constant in all the species of cast iron ; and a 

 few experiments made at that time on sandstone and marble, had led him to 

 suspect that nearly the same would be the case in these and other hard bo- 

 dies. Through the liberality of his friend Mr. Fairbairn (who had, as usual, 



p2 



