METEOROLOGY. 109 



The "nutrition" of the Leguminosae, L, Grandeau (Jour. Af/r. Prat., 60 (189G), 

 II, No. ,3G, Pi). S:J9-3S2). 



The flora of Alabama, P. H. Mell (Alahama College Sta. Bui. 70, pp. 276-296).— This, 

 bulletin, which is oue of ;i series to be devoted to the same subject, gives a list of 

 species of Leguminosio aud Rosace;e with their range throughout the State so far 

 as known. The series is to be continued as material accuniulatos without reference 

 to botanical sequence of families. 



Contribution to tlie Myxogasters of Maine, F. L. Hauvey {Torreij Bui., 2S 

 {1S9G), Xo. S, pp. 307-314). 



Notes on Indian fungi {Agl. Ledger, 1S95, No. 20, pp. 132, pis. 2, figs. 11). 



Capsicum, potatoes, and some other economic Solanaceee of India, Y. Ghosa 

 {Indian Agr., 21 {1S06), No. 7, pp. 209-212). 



A horizontal microscope, C. R. Barnes (Bat. Gaz., 22 (1896), No. 1, pp. 55, 56, pi. 

 1). — A description is given of a horizontal microscope devised by the author for the 

 measurement of the vertical growth of plants. 



METEOROLOGY. 



Injury from frost and methods of protection, W. H. Hammon 

 {U. S. Dept. Agy., Weather Bureau, pp. 12). — The conditions favoring 

 the formation of frost are popularly explained and the best locations 

 for orchards or gardens to avoid injury by frost and methods of frost 

 prevention are described, especially with a view to the needs of the 

 agriculturists of California. The use of the psychrometer in deter- 

 mining the dew-point is explained, with tables giving the dew-point 

 corresponding to dii^erent readings and temj)eratures likely to prove 

 injurious to 43 farm crops at 4 different stages of growth. 



"The experience of the past two seasons has shown that forecasts of sudden and 

 decided changes in temperature over a large territory are among the most accurate 

 made by the Weather Bureau ; consequently it is reasonable to expect that if suit- 

 able arrangements are made warnings may be received of those otherwise unex- 

 pected cool waves which will result in frost. There are instances, however, when the 

 general forecasts of the Weather Bureau can not be expected to .be sufficiently speciiic 

 to provide for the different conditions that may prevail in various sections. . . . 



"It is, therefore, necessary that the orchardist and gardener be able to judge, at 

 times, for themselves when danger from frost is imminent. For this purpose they 

 should be provided with a wet and dry bulb hygrometer or psychrometer, by which 

 the dew-point of the air can be deiterniined. 



"If, in the afternoon, the dew-point is near the critical temperature, arrangements 

 should Ije made for protecting, if necessary. If, at a later hour, the dew-point is 

 constant or lower, the sky clear or clearing, and the air calm, it is reasonable to 

 expect that the temperature will fall to the dew-point during the night. The efforts 

 to protect should be based on this dew^-point. If it merely approximates the danger 

 point (and no warning of more severe temperatures has been received) but little 

 protection will be necessary, and action may be delayed until the temperature is but 

 a few degrees above the danger point. However, if the dew-point be several degrees 

 below that liable to cause injury, or if it be falling, or if a change for the colder is 

 anticipated, efforts to protect should be undertaken earlier. The ground should be 

 irrigated during the day, smudge fires started when the temperature is several 

 degrees above the critical point, and, if the temperature contiuues to fall, the fires 

 should be sprayed until dense fog or mist envelopes the entire space. If the tem- 

 perature should then fall to the danger point, the trees aud plants should be thor- 

 oughly sprayed, at the same time keeping up the smudge and vaporizing fires. 



