Very good condition. Principal articles in the General Appendix include: Recent discoveries and theories relating to the structure of matter, by Compton, pp. 145-156; Aeronautic research, by Ames, pp. 167-174, 5 plates; Fogs and clouds, by Humphreys, pp. 187-222, 26 plates; The age of the earth, by Chamberlin, J.M. Clarke, E.W. Brown, & Wm. Duane, pp. 241-273; The tent catepillar, by Snodgrass, pp. 329-362, 1 plate; Collections of Old World archeology, by Casanowicz, pp. 415-497, 57 plates.