4 SCIENCE. 
‘Perhaps the most necessary and impor- 
tant instrument the Observatory ever had 
was the 9-inch transit circle, constructed, 
we believe, some timein the sixties. It was 
found so defective in stability as to greatly 
Attempts 
to correct the defect proved unavailing, so 
impair the value of its results. 
radical changes were made in the instru- 
ment at a cost, if we mistake not, which 
could not have been greatly short of the 
original price. No sooner was it remounted 
at the new location than defects were found 
in its performance which, according to the 
annual reports, it took another year to rem- 
edy. In 1896 it is reported as again taken 
down for a period of five months in order 
that further extensive repairs might be 
made. The report of 1899 gives an elaborate 
account of renewed efforts during the first’ 
six months of the year to improve its per- 
formance, concluding with the statement : 
“Tn my opinion it should be restored as 
nearly as possible to its original construc- 
But this does not end the history. 
We learn from the present report that the 
tion.” 
instrument was again undergoing repairs 
and alterations for the first six months of 
the last fiscal year, and yet it winds up with 
the statement that ‘‘ one of the defects still 
introduces liabilities to error which, though 
small, ought not to be tolerated in a modern 
instrument.” 
The defects in this instrument naturally 
Ac- 
cordingly, among the appropriations made 
led to the desire to have a better one. 
for the new establishment was one of 
$10,000 for a meridian circle. This instru- 
ment was completed and mounted in 1897. 
We learn from the report before us that it 
[N. S. Von. XIII. No, 314. 
exhibits a peculiarity of a kind so singular 
that it should interest physicists as well 
as astronomers. Its horizontal pointing 
changes so rapidly with the temperature 
that, by the aid of the delicate meridian 
mark, a variation produced by a change of 
asingle degree in the temperature must bean 
easily measurable quantity. Consequently 
the instrument could be used as a fairly 
delicate thermometer. It is hardly neces- 
sary to add that observations with such an 
instrument cannot have much scientific 
value until the defect is corrected, and, that 
the policy of the observers in not attempting 
serious work with it cannot be questioned. 
The new 12-in. equatorial has proved un- 
satisfactory. There are also intimations that 
something is wrong with the prime ver- 
tical transit, and, altogether, the impression 
made on the reader is that, after seven years 
of effort to equip the Observatory with the 
best instruments, it is doubtful whether a 
single one of real importance, except the 
great telescope, is in order for first-class 
work. We hope something can be said to 
explain this history, which is without ex- 
ample. The Greenwich transit circle has 
been in continuous use for half a century 
except during a brief period of its early 
history, when some alteration was made in 
it. The small repairs which it has since 
required have caused no interruption in the 
continuity of its work. The instruments 
of the Pulkova Observatory have, for the 
most part, been in use since 1840, and it is 
believed that their results are to-day among 
the best attainable in astronomy. 
Were only a single instrument involved 
in the case of our own Observatory, it might 
