118 SOME RESULTS OF AN ASTRONOMICAL EXPERIMENT 
I left Sydney on the evening of the 15th. On the morning of 
the 16th, at 8 a.m. the observatory (in parts of course) and the 
struments were left at Woodford by the train, and by the o 
evening of that day, and in spite of a steady gale of wind, the ob- . 
servatory was up and roofed, and the heavy parts of the instru- a. 
ment were in their places. On the second day we were able to 
begin observing about noon. 
The instruments consisted of (1) the 73-inch Merz tele- ; 
scope, with equatorial stand, clock driving gear, micrometer,eye-  ~ \ 
pieces, &e. ; (2) a 44-inch Cooke telesc ‘ope, 2g mounted ; 
(3) the large spectroscope, having dispersion of 18-64° prisms, : 
fine micrometer, and every a pliance to render it apie (4) : 
heliostat, driven by clockwork ; (5) electroscope, thermometers ij 
&e. Of the quality of the 73 telescope I need say nothing more 4G 
now than that it is a first-class instrument, as these sect will ae |. 
show, and well adapted for ms purpose. - 
The spectroscope was made by Hilger, of London, and at the is 
time (1576) it was considered the most powerful and perfect one 
in the world. : 
At 11°30 a.m. of the 17th eri I began the eae hie 
work, and was at once struck by the clear definition of the lin : 
the gain in clearness over the Byahey atmosphere was vel 
striking, but the next moment I asked myself where were the 
lines ; instead of seven lines between the two Ds there was but 
the Ds there was a shadin ng weiels as would be produc ore by veg 
fine lines, too faint to be seen separatel these bauer were 
i look at the spectrum until 
near sunset, when a great change had come over it. Six lines 
were visible between the Ds, and the usual host on either side; 
and as the sun approached the horizon they thickened very 
rapidly ; will be best understood by reference to the 
ings herew 
The sth October proved a cloudy day and night, fee a iat 
easterly wind or sea breeze. Towards morning of t 
clouds began to break, and soon after 9 a.m. m. the sun abet we 
At 10°30 there were a few passing clouds only, but the sky was 
fast, and by 11 a.m. it was difficult to make out the six lines, — 
ey also, were fading fast ; on either side there seemed to bea — 
shading such ae mh seen on the 17th. — oon the air lines 
had faded, and the spectrum appeared as 
