34 



SCIENCE. 



[N. S. Vol. I. No. 2. 



which were themselves in error about one- 

 tenth of a second and required subsequent 

 correction in other ways. Here then was a 

 lesson to astronomers who are all more or 

 less specialists, but it merely enforced the 

 perfectlj^ well known principle that the 

 constant errors of any one method are acci- 

 dental errors with respect to all other 

 methods, and therefore the readiest way of 

 eliminating them is by combining tile re- 

 sults from as many different methods as 

 possible. However, the abler the specialist 

 the more certain he is to be blind to all 

 methods but his own, and astronomers 

 have profited so little by the Encke-Hansen- 

 Lie Verrier incident of thirtj^-five years ago 

 that to-day they are mostly divided into 

 two great parties, one of whom holds that 

 the parallax can be best determined from a 

 combination of the constant of aben'ation 

 with the velocity of light, and the other 

 believes only in the results of heliometer 

 measurements upon asteroids. By all 

 means continue the heliometer measure- 

 ments, and do everj'thing possible to clear 

 up the mj'sterjr which now surrounds the 

 constant of aberration, but why ignore the 

 work of predecessors who were quite as 

 able as ourselves? If it were desired to 

 determine some one angle of a triangulation 

 net with special exactness, what would be 

 thought of a man who attempted to do so 

 by repeated measurements of the angle in 

 question while he persistently neglected to 

 adjust the net? And yet, until recently 

 astronomers have been doing precisely that 

 kind of thing with the solar parallax. I 

 do not think there is any exaggeration in 

 saying that the trustworthy observations 

 now on record for the determination of the 

 numerous quantities which are functions of 

 the pai-allax could not be duplicated by the 

 most industrious astronomer working con- 

 tinuously for a thousand years. How then 

 can we suppose that the result properly 

 deducible from them can be materially 



affected by anj-thing that any of us can do 

 in a lifetime, vinless we are foi-tunate 

 enough to invent methods of measurement 

 vastly superior to anj^ hitherto imagined ? 

 Probablj^ the existing observations for the 

 determination of most of these quantities 

 are as exact as anj' that can ever be made 

 with our present instruments, and if they 

 were fi-eed from constant errors they would 

 certainly give results very near the truth. 

 To that end we have only to form a system 

 of simultaneoiis equations between all the 

 observed quantities, and then deduce the 

 most probable values of these quantities by 

 the method of least squares. Perhaps some 

 of you maj' think that the value so obtained 

 for the solar parallax would depend largely 

 upon the relative weights assigned to the 

 various quantities, but such is not the case. 

 With almost any possible system of weights 

 the solar parallax will come out very nearly 

 8-809" ±0-0057", whence we have for the 

 mean distance between the earth and sun 

 92,797,000 miles with a probable error of 

 onlj^ 69,700 miles; and for the diameter of 

 the solar system, measured to its outermost 

 member, the planet ISTeptune, 5,578,400,000 

 miles. William Haekness. 



Washington. 



THE BALTIMORE MEETING OF THE AMERI- 

 CAN SOCIETY OF NATURALISTS. 



The thirteenth annual meeting of The 

 American Society of Naturalists was held at 

 Baltimore during the Christmas vacation. 

 Considering that Baltimore is the southern 

 limit where meetings may be held by the 

 Society, the attendance was large, forty to 

 fifty members being present. 



The first session was called to order by 

 the President, Professor Charles S. Minot of 

 the Harvard Medical School, at 2 p. m. on 

 Thursday, December 27th. 



A quorum being present, the Society at 

 once proceeded to the transaction of busi- 

 ness. The committee appointed in 1893 to 



