Jourrul of the Franklin Institute, 708, December, 1884.—G. Forbes, dynamo-electric machinery; a full report of the lecture given by Brof. Forbes at the Philadelphia Exhibition.—R. H. Thurston, steam boilers as magazines of explosive energy. This paper contains lengthy numerical tables of the energy, expressed both in footipounds and in kilogrammetres, stored up in boilers containing given weight of water or steam at given pressures. According to these calculations a Lancashire two-flue boiler holding three tons of water working at 37 lbs. of steam pressure would, oy its explosion, liberate sufficient energy to blow itself nearly 2,1/2 miles high, with an initial velocity of 900 feet per second.—E. J. Houston, glimpses of the International Electrical Exhibition, Nos. 2 and 3. These papers give accounts of Dolbear's electrostatic system of telephony, and of Gray's telephonic inventions, with numerous illustrations.—L. d'Auria, the earth's ellipticity; a reply to Prof. Chase.—Standard sizes of belt heads and nuts, a reply by Mr. Coleman Sellers to Mr. Simtnonds.