• 71 Roj^al Institution of Great Britain. 



May 4. — Mr. Cottam on the application of cast-iron to bearing 

 purposes, especially in the form of beams, girders, brackets, &c.&c. 

 — After explaining that the elastic force of a bar was the utmost 

 weight which it could bear, so that upon its removal the bar should 

 return to its original form, and showing by experiment that this was 

 very much less than the breaking force, he stated that it was of the 

 utmost consequence to attend to the limit of elastic power. If the 

 material be strained beyond that point, and the straining force be 

 suffered to remain, or frequently repeated, the deflection continues 

 to increase, and fracture ultimately takes place; but if the load be 

 restrained within the limit of elastic power, it may be suffered to re- 

 main for any length of time with perfect safety, and without in- 

 creasing the deflection in the smallest degree. 



In the various experimental illustrations it appeared that a bar 

 supported at both ends, when loaded with 189 pounds in the centre, 

 or 236 pounds distributed at equal distances over its length, was 

 equally deflected. When the length of the bar was reduced one 

 half, the weight supported at the centre was doubled. A bar sup- 

 ported 378 pounds without receiving any_set, i. e. it remained capa- 

 ble of returning to its original form when the weight was removed. 

 This was the limit of its elastic power: it broke with 556 pounds. 



From the various experiments the following practical rule was 

 drawn. Multiply 850 times the breadth in inches by the square of 

 the depth in inches, and divide the product by the length of bearing 

 in feet ; it will give the weight to be supported in pounds at the 

 middle of its length, or twice that weight distributed uniformly oveF 

 its surface. '' 



May 11, — Mr. Cowper on recent improvements in tlie loom for 

 weaving silk. — Mr. Cowper's object was principally to explain the 

 construction of the Jacquand loom, and the nature of the innumer- 

 able changes therein produced, and which are requisite for any rich 

 figured pattern. He had drawings and models of many preceding 

 looms, and illustrated his details by numerous contrivances; but 

 we are unable, without figures, to convey any notion of the beauti- 

 ful principles which in this loom are put into practice. 



Afterwards Professor Ritchie showed the inflammation of oxygen 

 and hydrogen gases by the electric spark obtained by magneto- 

 electric induction ; and Mr. Faraday showed the spark itself to all 

 present by means of the arrangement already described, Phil. Mag. 

 and Annals, N. S. vol. xi. p. 405. 



May 18. — Mr. Faraday on the crispations of fluids lying on 

 vibrating surfaces. — This was a development and demonstration of 

 the principles by which Mr. Faraday explains certain curious modi- 

 fications of the forms of fluids supported on vibrating plates. The 

 investigation forms part of a paper published in the Philosophical 

 Transactions for last year, but not read before the Royal Society for 

 want of time. We refer to the paper for details, and for the, ex- 

 tensions of the principles which the author puts forth. 

 . May "-ZS. — Mr. Brockedon on the Pering anchor. The various 

 improvements made in the form of the anchor by Mr. Pering hav« 



