72 E.S8. Holden—Observations of the Transit of Venus. 
Preparations for the Transit.—The ies telescope had its 
sale reduced as described. A positive eye-piece maar 
195 times, with a field of 11’ 42”, was fitted to one o 
Clark's reflecting solar eye-pieces. This was carefully focused 
on the sun and on stars on several occasions, and the tube was 
set at a mean reading of the focussing-scale. 
Marks were put on the tubes by which the positions were 
recoverable at any time. A pair of cross- -wires (platinum) was 
inserted in the eye-piece and the sun’s light was reduced by a 
Steinheil “ moderating: glass,” An easy ae construction 
assured me of the exact point of first conta 
he 6-inch telescope was also provided with a Clark’s solar 
eye-piece, to which a positive eye-piece magnifying 176 times 
was fitted. A pair of crossed platinum wires was also fixed in 
front of this eye-piece. The focal point and the point of first 
contact were determined independently by Mr. Comstock and 
myself. 
All the preliminary adjustments remained constant till after 
the Transit. The time was determined by observations of 
twenty stars on the nights of December 4th, 5th and 7th. All 
time-pieces were referred to the Hohwa sidereal clock. The 
Washington time-signals were received on December 5th and 
6th, and it may be mentioned that the resulting longitude of 
the Washburn Observatory differs from ot ‘adopted soa 
by considerably less than one-tenth of a second of time. All 
sidereal times here given are al all mean times are Chicago 
mean times, and are 5 7m 11%11 later than local mean times. 
Geographical positions.—The position of the large chads p is 
as follow 
Lengitede W. from Washington, 0" 49" 25°78, Latitude 
-+ 48° 4' 367°8, 
The position of the small telescope is as follows: 
ee W. from Washington, 0" 49" 25°60. Latitude 
+43° 
eae —The following is a transcript from my observ- 
ing-book: ‘Dome opened 19" 30". 19" 45". Image of sun 
extremely unsteady. [The times are noted on sidereal chro- 
nomete rs. 
ae 13 8" 0°+. Through clouds and haze: sun unsteady, 
and the lightest part of the Steinheil wedge used. I could not 
have observed with the usual shade-glass. Time uncertain by 
5° or perhaps 10°, though I think not more than 5° Venus 
entered exactly at the point where wires were set. At 20" 27™ 
(Chicago m. t.) the whole dise of Venus is seen, and a little 
ring of light outside it, This was not specially looked for, but 
is first seen now. 
