ASTRONOMY. 315 



uals on four nights by Prof. W. A. Eogers, of Cambridge, and Dr.Waldo, 

 an exchange of observers being made on two nights. The difference of 

 longitude between the meridian circle of Harvard College Qbservatory 

 and the transit of Yale College is 0^ 7°^ 10^353 ± 0^0091. 



This report also contains the second annual statement of Dr. Waldo, 

 astronomer in charge of the horological and tbermometrical bureaus of 

 the observatory. This kind of work has not been undertaken anywhere 

 else in this country; and the manner in which it is done reflects credit 

 on all concerned. 



LicJc Observatory. — The Lick trustees have ordered from Messrs. Eep- 

 sold, of Hamburg, a 6-inch meridian circle of the design of that of the 

 Strasburg Observatory. The objectives of the instrument and of the 

 north and south collimators are of six inches aperture, and will be made 

 by Alvan Clark & Sons. The objective and eye end of the circle are 

 interchangeable. There are two divided circles, A and B. A is fixed on 

 the axis and divided to 2'. B is movable on the axis and is divided to 

 2' at four points 90° from each other. Every degree of each circle is 

 numbered with an engraved figure. There are four microscopes to each 

 circle, one revolution of their micrometers being 1', and one part being 

 1". The setting is done by a reflecting microscope with two eye-pieces, 

 one north, the other south. The axis of the circle is itself a telescope, 

 and a collimator east or west is used to rectify its position. The hang- 

 ing level is so arranged that it can be applied while the instrument is 

 l^ointed to the nadir. 



The flint disk for the 36-inch objective to be made by Alvan Clark & 

 Sons for the Lick Observatory has arrived in this country. Its diameter 

 is 97'='" (38.19 inches), its thickness oo^"! (21.65 inches), and its weight 

 170 kilograms (375 i)ounds). A month was required in the cooling. 

 A crown disk has also been cast by M. Feil (fils) who made the flint. 



A sidereal clock ordered by the Lick trustees, from A. Hohwu, of 

 Amsterdam, has arrived in this country. It is in all respects similar to 

 the normal clock of the Washburn Observatory, described in its publi- 

 cations. Vol. 1, 1881, p. 12 ; and to a clock just delivered to the Pulkova 

 Observatory. Its cost is about $447. Similar clocks are mounted at 

 the observatories of TJpsala, Leyden, Strasburg, Brussels, and Tashkent. 

 This clock bears the number 33. 



West Point Academy. — Alvan Clark & Sons are making a 12-inch equa- 

 torial for the observatory of the LTnited States Military Academy at 

 West Point. 



The following list of dates may have some interest : 

 The collimating eye-piece was first proposed (by Bohnenberger) 



in the Astronomiche Nachrichten, Vol. TV, -p. 330 in 1825 



Used at Madras Observatory . 1834 



Tried at Konigsberg 1837 



Used at Edinburgh for nadir 1840 



Used at Oxford for nadir 1843 



