410 



SCIENCE. 



[N. S. Vol. XII. No. 298. 



besides can be made out of the physical mixture 

 of red and green and blue. That fact has been 

 put beyond doubt, once for all, by the exceed- 

 ingly exact measurements of Professor Konig, 

 made by means of an instrument of very in- 

 genious construction (and so expensive that it 

 has been duplicated for hardly any other labor- 

 atories). There is not a psychologist who denies 

 this physical fact, and for the physicist to con- 

 stantly re-afflrm it, and to say that it has received 

 fresh proof (see the report of the last meeting 

 of the scientific societies in New York) is 

 much the same as if he should valiantly af- 

 firm that one side of a shield is of silver by way 

 of opposition to those who say that the other side 

 is of gold. What the psychologist denies is not 

 that gray results when blue and yellow are 

 mixed upon the color wheel — he has admitted 

 that long ago, and it will be found as an elemen- 

 tary statement in every text-book of psychol- 

 ogy. But he refuses to admit, nevertheless, 

 that white is an even red-green-blue sensation 

 in the same sense in which purple is an even 

 red-blue sensation. It is here that the adher- 

 ents of the Young-Helmholtz theory should 

 attack him. 



C. Ladd Franklin. 



A LARGE CRYSTAL OF SPODUMENE. 



To THE Editor of Science : There has 

 recently appeared in some scientific journals a 

 notice of a crystal of spodumene stated 

 to be about twenty-nine feet long, and to be 

 the largest known. It may be of interest to 

 your readers to learn that a much larger 

 crystal has been observed. In the year 1885 

 while studying the tin ore or cassiterite 

 localities of the Black Hills of Dakota I saw 

 and measured, in the Etta tin mine near 

 Harney's Peak, a spodumene crystal thirty- 

 eight feet and six inches in length and thirty- 

 two inches in thickness. This thirty-eight and 

 a half foot crystal was almost perfect, and was 

 situated within a few yards of the surface. 

 Owing to its size and the difficulties of trans- 

 portation at that time, the railway being one 

 hundred and thirty miles distant, I made no 

 attempt to have the crystal removed. I, how- 

 ever, collected other crystals of spodumene in 

 the vicinity, and some of these measured from 



two to six feet in length. Subsequently, in a 

 public lecture upon the Black Hills, given in 

 the University of North Dakota in February, 

 1886, I announced the discovery of the afore- 

 said gigantic crystal ; but, because of the pres- 

 sure of teaching and other numerous duties, 

 that discovery has not been reported in the 

 regular scientific journals. 



For the benefit of some readers it may per- 

 haps be well to state that spodumene is a 

 grayish-white or pink mineral of considerable 

 hardness, being nearly as hard as quartz, and 

 that it consists of silica, alumina and lithium. 

 Henry Montgomery. 



Trinity University, Toronto, 

 July 17, 1900. 



UNITS AT THE INTERNATIONAL ELEC- 

 TRICAL CONGRESS* 



At the suggestion of Professor Hospitaller, 

 Section I. of the Congress agreed that the fol- 

 lowing should be the members of the Commis- 

 sion on Units : Messrs. Ayrton (Great Britain), 

 De Chatelain (Russia), Dorn (Germany), De 

 Fodor (Hungary), Eric Gerard (Belgium), 

 Hospitaller (France), Lombardi (Italy), Ken- 

 nelly (United States) ; and at the first meeting 

 of the Commission, on August 21st, which was 

 attended also by Professor F. Kohlrausch and 

 Sir W. Preece — whose names had been added 

 to the list of the government delegates for Ger- 

 many and England — a report presented to the 

 Congress by the American Institute of Elec- 

 trical Engineers was taken into consideration. 

 This report had been drawn up for that Insti- 

 tute by a committee appointed for this purpose, 

 and it contained the following resolutions : 



(1) We consider that it is necessary to give 

 names to the absolute units in the electromag- 

 netic and electrostatic systems, as well as con- 

 venient prefixes to designate the decimal multi- 

 ples and submultiples of these units in addition 

 to those already in use. 



(2) The International Congress of Electricians, 

 which will take place this year in Paris, should 

 be invited to choose the names and the prefixes. 



(3) A great advantage would be gained by 

 a rationalization of the electric and magnetic 



*From Nature. 



