142 THE HAMILTON ASSOCIATION. 
of the object glass, is good definition, when climatic conditions are 
favorable, as I can testify from many repeated observations. 
Attached to the Observatory proper is a very handy Transit 
Room, to which reference will be made later, and also a Laboratory, 
containing chemicals of assortment, two lathes, and many necessary 
appliances in the construction of scientific instruments. 
The principal telescope in the Observatory is a Refractor of 5 
inches aperture and 82 inches focal length, the object glass and tube 
of which were manufactured by Prof. J. A. Brashear, of Alleghany, 
Pa., an optician of world-wide reputation and of whose work it 
would be superfluous to add any praise. All the fittings to the 
instrument were made by Dr. Marsh. It is mounted equatorially 
and driven by clockwork to counteract the motion of the earth, 
which enables a star to be examined for an indefinite period in 
apparently a fixed position in the sky. ‘The telescope has a battery 
of eight eyepieces ranging from 50 to 550 powers. In addition to the 
above it is fitted with a Brashear micrometer, star and solar prisms, 
a photographic attachment, together with a spectroscope (also by 
Brashear) with rotary grating and two eyepieces of 150 and 200 
powers, for viewing the solar prominences. Lastly, but by no means 
least, the telescope is fitted with double hour and declination circles 
of 6 inches diameter, graduated to read seconds of arc, and made 
on the premises. It is only those who know the luxury of using this 
device, by which the instrument can be turned to an object, although 
invisible to the unaided eye, that can appreciate the time and labor 
saved in the course of working with a telescope equatorially mounted. 
I feel I am justified if I go out of my way here just to give an 
instance of the truth of the old saying, ‘ Necessity is the mother of 
invention,” and of comparing the happy position of our President 
with another astronomer in a humble sphere of life whom I knew, 
and had the honor of writing an account of his work in the trans- 
actions of the Astronomical Society of Wales ten years ago. Like 
Dr. Marsh, he felt the need of graduated circles with his home- 
made telescope, but, alas, he was poor and could not afford to buy 
the orthodox, costly article of brass ; so he constructed them him- 
self out of slate! Surely the first of their kind and last in existence. 
They read to minutes of arc, and are now preserved in the museum 
of Bangor city. But with finer tools, and consummate skill for an 
