WATER SOILS. 545 



The relation of weather to crop production, J. W. Smith (Jour. Columbus 

 Hurt. Soc, 19 ( 1904), No. 3, pp. 80-84)- — Mainly a summary of an article in the Year- 

 book of this Department for 1903 (E. S. R., 16, p. 136). 



Weather influences, E. G. Dexter (New York: The Macmittan Company, 1904, 

 pp. XXXI A-286, Jigs. 52). — This book discusses sources and nature of weather prov- 

 erbs, the weather lore of the "skyey influences," animal weather lore, weather 

 influences in literature, the empirical problem, the meteorological conditions, the 

 child and the weather, crime and the weather, insanity and the weather, health and 

 the weather, suicide and the weather, drunkenness and the weather, attention and 

 the weather, and a summary of weather effects. A bibliography of the subject is 

 included. 



The humidity of the air of our homes, II. F. Bisnop (Engineer. News, 52 (1904), 

 No. 11, pp. .'14-236, figs. 2). — This question is somewhat fully discussed, the author 

 stating in conclusion his belief " that a humidity of 30 to 50 per cent, depending upon 

 outside conditions, can be readily maintained, will be found sufficient for comfort, 

 and conducive to the best health." 



A sensitive hygrometer, W. M. Thornton ( Abs. in Nature [London}, 71 (1904), 

 No. 1828, p. 47).— A paper read before the Physical Society, October 28, 1904. 



"The instrument is made by enclosingthe cooled surface of a Regnault's hygrometer 

 in a glass globe, so that only the mass of vapor contained in the vessel is available 

 for condensation. The cooled surface is made much smaller than usual — about 1 

 scj. cm. The surface-density of the deposited moisture depends on the total quantity 

 of water vapor present. If this is more than a minimum to be determined later, it 

 will be visible either by the loss of brightness by scattering, or by observing, as in 

 the Dines hygrometer, the scattered light itself. 



"Little is known as to the manner in which moisture is deposited on smooth, cold 

 surfaces. Dr. Park has shown that the thickness of the deposit is of the same order 

 as that of the black spot in interference films. The reflection of light from such a 

 clear layer of uniform thickness backed by a bright surface is considered in the paper, 

 and it is shown that the loss of light due to the thinnest possible films can be per- 

 ceived. The opposite case to that of a smooth layer is that of clear spherical particles 

 resting on the surface. This is also considered, and the surface-density to give a 

 visible deposit is calculated. In connection with this an interesting note was received 

 from Lord Rayleigh in reply to an inquiry, in which he shows that the maximum 

 brightness of a cloud is about 4X10- 5 that of the sun. 



"Comparing all values, it is taken that 10~ 8 gm. per square centimeter can be 

 detected by unaided vision with diffused light. The time taken for moisture to 

 diffuse from a state of uniform distribution throughout the globe toward the center 

 is then calculated, and found to be less than 10 minutes for a sphere of 20 cm. 

 diameter. The paper is an attempt to make the somewhat neglected Regnault 

 hygrometer an instrument of precision in the detection of small quantities of 

 moisture." 



Studies on the circulation of the atmospheres of the sun and of the earth, 

 F. H. Bigelow ( U. S. De/it. Agr., Weather Bureau Doc. 316, pjt. 44, figs. 24, charts 16). — 

 Reprints of articles previously noted (E. S. R., 15, p. 856; 16, pp. 25, 236, 237). 



On the general circulation of the atmosphere in middle and high latitudes, 

 W. N. Shaw ( U. S. Dept. Agr., Weather Bureau Doc. 314, pp. 13, figs. 4). — This is a 

 reprint of an article previously noted (E. S. R., 16, p. 237). 



WATER- SOILS. 



The progressive sinking of the ground water level and artificial ground 

 water supplies, J. (i. Richert (Engineer. News, 52(1904), No. 21, pp. 474, 475, 

 figs. 7). — The sinking of the ground water level as a result of excessive pumping is 

 discussed, and the so-called Swedish system of raising the level and increasing the 



