328 0. A. Young—Observations of the Transit of Venus. 
The filar micrometer measures consisted of 8 sets of 10 read- 
ings each, at position angles differing by 45°, They give: 
Pos. angle, 0° and 180°___--- 64°29 
* i Ane S25". 3S 64°43 
WU 0G 270. pau 63'°93 
Ms 186° and 315°.._..2 64°57 
Mean 64°23 
Reduced to distance unity, 16’-99. 
The difference of 2’1 between the double-image and filar 
micrometer is more than would have been anticipated, and I 
am not now able to explain its magnitude. I shall reéxamine 
the micrometer constants, but suspect the difficulty lies in the 
observer. 
The double-image micrometer gave a power of about 600, 
and the images were always very pale and sometimes almost 
invisible; they were at no time sharply defined, clouds being 
very troublesome nearly all the time. ‘The power used on the 
filar micrometer was about 250. During its use the seeing was 
much better than it had been during the double-image observa- 
tions; it was never really very bad, and much of the time 1 
Pines good, so that the details of the solar surface came out 
nely. 
VII. Sprecrroscoric OpsERVATIONS, 
Spectroscopic observations were made both by Mr. McNeill 
and myself. Immediately after second contact I uncovered the 
whole aperture of the telescope, and attached the Clark spectro- 
Scope with a diffraction grating of about 17,000 lines to the inc}. 
The slit was made tangent to the limb of the planet at the point 
most remote from the sun’s center. I first tried the spectrum 
of the first order, examining specially B, a, and the interval 
] 
between Cand D. The clouds at the time were pretty thies 
