10 REl'ORT — 1855, 



On the Phcenomena of Decomposed Glass. 

 By Sir David Brewster, K.H., F.R.S. L.S) E. 



These papers were illustrated by elaborate drawings of the phsenomena. 



On the Making and Magnetizing of Steel Magnets. 

 By Paul Cameron, Glasgoio. 



The author records a few experiments in the forging, softening, hardening, and 

 magnetizing of them. He procured one dozen of magnets : four of them were 

 forged, hardened, and magnetized north and south ; four were forged, hardened, and 

 magnetized N.E. ; and the remaining four were foiged, hardened, and magnetized 

 east and west. One dozen compass needles were forged, hardened, and magnetized 

 similar to the above ; four of the compass needles were enclosed in an iron case 

 filled with fresh lime ; the case was then put into a fire until it became a deep red, 

 and was then covered up and allowed to cool slowly. The needles were then 

 dressed and hardened in afire mixed with bone-dust, the bone-dust being mixed with 

 charcoal and lime, which would further increase the quality of the steel. 



The average magnetic powers of the magnet before magnetizing were as follows : — 



The magnetic powers of the bars hardened N. and S. from V to 10. 



N.E. ... 5° to 7°. 



E. andW. ... 1° to 2°. 



He then placed a large copper coil, having an inclination corresponding with the 

 dip, in the magnetic meridian, and connected the coil with the poles of a galvanic 

 battery containing thirty-six pairs of plates ; passed and repassed the magnets that 

 were hardened N. and S. ; placed the coil in a N.E. direction, and passed and re- 

 passed the magnets hardened N.E. ; and then placed the coil in the direction E. and 

 W., and passed and repassed the magnets that were hardened E. and W. 



The magnets hardened and magnttizedN. and S., average deflection from 43° to 45". 



N.E. ... ... 36° to 38°. 



E. andW. ... ... 20' to 22°. 



A similar result followed after the needles were passed through the coil. 



On the Deviations of the Compass iti Iron Ships and the means of adjusting 

 them. By Paul Cameron. 



On an Analogy betiveen Heat and Electricity. 

 By the Rev. Professor Chevallier. 



Arago, in his posthumous work on lightning (CEuvres de Francois Arago, Notices 

 Scientifiques, torn. i. Paris, 1854), distinguishes three classes of lightning, of which 

 the third is that which takes the form of a fire-ball. 



He produces many examples (chap. vi. vii.), the principal facts being, that during 

 a thunder-storm balls of fire are sometimes seen ; that thej' sometimes move very 

 slowly, not faster than a mouse (ch. vii. § 3), so that, in a room, a person may get 

 out of their way (ch. vii. § 6), rolling over and over like a kitten, or may follow 

 them for a considerable distance on foot (ch. vii. § 5) ; that for a time the presence 

 of such a ball may produce no injurious effect ; but that it usually explodes at last 

 with prodigious violence. 



It does not seem to have been pointed out, that this form of electricity bears a 

 remarkable analogy to the spheroidal form which fluids assume when in apparent 

 contact with bodies intensely heated. The attention of the Section was invited to 

 the subject. 



On the Polyslereopticon. By An^joine Claudet, F.R.S. 



