1 



February 2-t, 1905.] 



SCIENCE. 



309 



under the action of radium rays. The gases 

 were enclosed in a vessel in such a way that 

 a small change of pressure could be observed. 

 About four milligrams of radium bromide 

 were dissolved in alcohol and deposited on the 

 surface of a small sheet of platinum which 

 was placed in the vessel. 



By means of electrodes the amount of ion- 

 ization produced in the gas by the radium was 

 measured. While the rate of formation of 

 water was quite slow, yet the number of 

 molecules of water formed for each physical 

 ion produced was very large. The experi- 

 ments are being continued by Professor Ed- 

 wards. 



C. C. Trowbridge, 



Secretary. 



THE PHILOSOPHICAL SOCIETY OF WASHIX(;TON. 



At the 593d regular meeting, the 34th an- 

 nual meeting, held December 24, 1904, the fol- 

 lowing officers were elected : 



President — G. W. Littleliales. 



Vice-Presidents — Cleveland Abbe, J. G. Hagen, 

 A. L. Day, L. A. Bauer. 



Treasurer — Bernard R. Green. 



Secretaries — Charles K. Wead, Lyman J. Briggs. 



General Committee, besides those named above 

 — W. A. De Cundry, H. M. Paul, J. Winston, L. A. 

 Fischer, R. A. Harris, E. B. Rosa, C. G. Abbott, 

 K. E. Guthe, W. S. Eichelberger. 



The secretaries' and treasurer's reports 

 showed that the society is in a prosperous con- 

 dition, having had a considerable increase of 

 membership during the past year. 



The 594th regular meeting was held Jan- 

 uary 7, 1905. 



The first paper was by Mr. E. P. Hyde, of 

 the Bureau of Standards, by invitation, on 

 ' Some Problems of Photometry.' These re- 

 lated mainly to the rating of electric incan- 

 descent lamps, and to practical methods of 

 obtaining the mean spherical illumination ap- 

 plicable to the various forms of lamps with 

 their widely differing filaments and distri- 

 bution curves. In the Matthews photometer 

 there are a number of pairs of mirrors, the 

 centers of one set lying in a meridian of the 

 lamp and throwing the rays to the mirrors of 

 the other set, whence they go to the screen. 



The lamp is rotated about 180 times per sec- 

 ond. The speaker had determined the angular 

 position of the mirrors of the first set that 

 would give theoretically accurate results for 

 three extreme cases of distribution, and then 

 found an average position that reduces ma- 

 terially the small errors of the Matthews in- 

 strument. 



Mr. W. J. Spillman, in charge of the forage 

 plant investigations of the Department of 

 Agriculture, then spoke on ' Utilizing the 

 Desert,' dealing with the cactus and its uses, 

 and showing many slides. 



It has been found that the cactus plant 

 possesses considerable value as feed for cattle, 

 sheep and hogs. It is universally used by 

 Mexican freighters in southwest Texas for 

 their work oxen, and in famine years it is 

 used by stockmen generally to tide over the 

 dry periods) and for this purpose it possesses 

 great value. The possibility of utilizing 

 cactus frequently saves the wiping out of vast 

 herds of cattle in time of famine. Several 

 methods are in vogue for getting rid of the 

 spines preparatory to feeding cactus. One 

 of the most common is to scorch off the spines 

 over a brush fire. A modification of the 

 plumbers' torch is more or less extensively 

 used for treating cactus in place. Many stock- 

 men use a specially constructed cutting ma- 

 chine which pulps the cactus and abrades the 

 spines so that the juices of the plant quickly 

 render the spines innocuous. The pulped ma- 

 terial is readily eaten. Some steam the 

 cactus in large vats, which so softens the 

 spines that they become harmless. Some 

 varieties of cactus will thrive with one rain 

 a year; and averaging a period of years an 

 acre of cactus is equal to an acre of ordinary 

 forage plants. 



At the 595th meeting, January 21, 1905, 

 Dr. Guthe exhibited a bar of Heusner's alloy 

 composed of 60 per cent, copper, 27 per cent, 

 manganese and 13 per cent, aluminum, which 

 is strongly magnetic, though none of its con- 

 stituents is so. 



Mr. Abbott exhibited and described ' A Com- 

 parator with Planimeter Attachment ' espe- 

 cially devised for reading ordinates, abscissae 

 and areas of curves on 10-inch by 24-inch 



