668 
detail shown by them, are surprising. 
Many new features are shown, and some 
general conclusions of the highest interest 
have already been drawn. From one to 
sixteen new nebule have been found on 
nearly every plate exposed, and I have esti- 
mated that the number of new nebule in 
the sky, within reach of the Crossley re- 
flector, may be something like 120,000. A 
set of photographs made with the Crossley 
telescope was exhibited at the conference of 
astronomers recently held at the Yerkes 
Observatory, and has since been presented 
to the Royal Astronomical Society. 
An investigation in the distribution of 
stars in the Great Cluster in Hercules, by 
means of a photograph taken with the 
Crossley telescope, has been made by Mr. 
Palmer. 
Following a method which I proposed 
some years ago, the Crossley telescope has 
been used to produce photographs of the 
Great Nebula in Orion, by means of the less 
refrangible rays of the spectrum, which are 
directly comparable with drawings. The 
results are in confirmation of earlier spec- 
troscopic observations made here, and may 
be regarded as an extension of the spectro- 
scopic method to parts of the nebula which 
are too faint for visual observation. 
THE TWELVE-INCH REFRACTOR. 
This instrument is in charge of Professor 
Hussey, who is assisted by Mr. Coddington. 
A most important part of its work, as well 
as that of the 36-inch telescope, is the 
measurement and discovery of double stars, 
for whieh purpose the conditions on Mt. 
Hamilton are especially suitable. Professor 
Hussey is at present engaged in the re- 
measurement of all the Otto Struv stars, or 
double stars discovered at the Pulkowa Ob- 
servatory. About 2,000 measures have been 
made in connection with this work up to 
the present time. 
The number of measures of double stars 
SCIENCE. 
[N. S. Vou. X. No. 254. 
made during the past yearisas follows: By 
Professor Hussey, 996; by Mr. Aitken, 
976. Mr. Aitken’s list includes nearly all 
the rapid binary systems. 
A systematic search for new pairs has 
been made by Professor Hussey, mainly 
with the 36-inch refractor, within the zone 
10° to 14° south declination. Thirty-six 
new pairs were found during the past year, 
most of them very close, the distance in 
two cases being only 0.15. 
The zone between 2° and 10° south decli- 
nation has been examined in a similar 
manner, with the the 12-inch equatorial, by 
Mr. Aitken. About 50 pairs have been 
found since April Ist of the present year. 
To guard against errors, each new pair has 
been examined with the 36-inch telescope 
on at least one night. Only close stars 
brighter than the 9th magnitude are in- 
cluded in these lists. 
With both equatorials the following com- 
plete sets of comet observations have been 
made during the year ending September 1, 
1899: 
Comet. No. Obs. and Observer. 
1898, I. (Perrine). 21, Perrine. 
1898, IV. (Wolf). 8, Hussey. 
1898, VII. (Coddington) 9, Coddington. 
1898, VIII. (Chase). 1, Aitken, 36 Coddington. 
1898, IX. (Perrine). 20, Perrine. 
1898, X. (Brooks). 19, Hussey. 
1899, a (Swift). 7, Hussey ; 17, Perrine. 
1899, b (Tuttle). 13, Perrine. 
1899, c (Tempel II.). 2, Hussey ; 10, Aiken. 
31, Perrine. 
1899, d (Holmes). 5, Aitken ; 9, Perrine. 
Total number of comet observations, 208. 
At the request of Professor Simon New- 
comb, the asteroids discovered by Professor 
James C. Watson have been observed for 
the National Academy of Sciences. The 
work has been done by Mr. Coddington. In. 
general, ephemerides were computed from 
the data given in the Berliner Jahrbuch. The 
region indicated by the ephemeris was. 
photographed with an exposure of one hour 
