212 ASTRONOMY. 



precedingly defined iustant is that when this equality ceases or is es- 

 tablished. 



The observer should also note whether there is produced on the 

 luminous thread any fringes or any other distinct phenomena, and 

 should note the moment of their appearance and disapj^earance. 



Tt is generally desirable to note the time of occurrence of any distinct 

 phenomena about the time of contact. ISTevertheless it is a grave mis- 

 take, and one that should be guarded against, to multiply the noting of 

 times near the occurrence of a contact. 



The time of appearance of phenomena of a distinct character should 

 be mentioned only in such a manner as to be readily separated from 

 other phenomena observed about contact. 



It will be useful in all cases that the observer should illustrate his 

 notes with a drawing made immediately after each complete observa- 

 tion of contact, in order to show more clearly the interpretation which 

 he attaches to his description of the phenomena. 



Art. 5. As the limb of Venus falls internally on the solar disc during 

 internal contact, as has been noted in Article 4, the observer should 

 indicate as closely as possible whether the moment when the limbs 

 of Venus and the sun, apparently coinciding, seem to be lengthened 

 out. 



This observation, though rough, is still desirable as a check to the 

 principal noted phase. 



Art C. Notwithstanding the fact that observations of external con- 

 tacts are subject to considerable uncertainty, the conference recom- 

 mends that they be observed either by direct vision or by means of the 

 spectroscope, and that the point on the solar disc, where the first con- 

 tact takes i)lace, be determined in an appropriate manner." Gomptes 

 Mendus, October, 1881. 



The Austrian Government will be petitioned to grant a subvention 

 towards equipping an expedition to take part in the observation of the 

 next transit of Venus, on 6th of December, 1882, as the next opportu- 

 nity of thus measuring the distance of the earth from the sun will not 

 occur till the year 2004. The Bermudas are recommended as the most 

 suitable observation station. 



Transit of Mercury, November 7, 1881. — A noteworthy fact in relation 

 to this transit is the expedition of Mr. C. H. Eockwell to the Sandwich 

 Islands for the purpose of observing it. Only two contacts could be 

 seen in the United States, and so Mr. Eockwell left his observatory at 

 Tarrytown and arrived at Honolulu on November 4. On November 7 

 he observed all four contacts and a number of diiferences of R. A. of the 

 sun and INIercury, and on the 8th sailed for the United States. 



The only other American observation of which we know was made at 

 the new Lick observatory by Prof. E. S. Holdcn and Mr. S. W. Burn- 

 ham, who observed the first and second contacts. 



The transit was well observed in Australia. 



