62 
the aperture for about 53° on the Southern side, which was 
found to be the utmost that the strength of the edifice per- 
mitted, and it was found necessary to compensate even this 
gain by introducing transverse bars of iron, and nearly one 
seventh part, 12 out of 88, of the standard stars of the Nau- 
tical Almanac still remained hidden from view. 
The magnetic and meteorological observations carried om 
at the same time by Capt. Gilliss were probably as laborious, 
and were certainly as conscientiously prosecuted as the astro- 
nomical ones. They were subsequently reduced and pub- 
lished, the last volume appearing in the same year with that — 
containing the astronomical results. 
I have said that Gilliss’s volume of observations was the 
first one published on our side of the Atlantic, and have 
shown how, in spite of many and serious obstacles, his com- 
scientious assiduity and unwavering zeal accomplished not 
only all that his instructions required, but much more than 
this. It remains to speak in this connection of the charac 
ter of the observations and their results. 
I need not remind you, gentlemen, how many an accom- 
plished practical astronomer lacks that delicacy of the 
senses, and those other physical powers, by which alone the 
most refined observations may be attained. Even the bem 
observers have not always the highest qualification in these 
respects; for a quick ear, a sharp vision, and a delicate touch 
are by no means all that constitute the highest skill in an 
observer. The refined methods of observing, the adroit 
precautions against incidental errors not dependent upo® 
the senses, the ingenious devices for detecting, measurings o. 
and allowing for errors unavoidably incurred, as distine 
guished the simple endeavor to avoid them,—™ 
A endeavor of which the success must necessarily be mor? 
re ay the limits of our senses, however basil: 
