ASTEONOMY. 287 



eter, in vacuo, rose 130° Fahrenlieit, while the temperature in a black- 

 ened copper vessel, covered by two sheets of common window glass, rose 

 above the boiling point. TVith such a vessel water could be boiled amoug 

 the snow-fields of Mount Whitney by the direct solar rays. 



AVhile the influence of the atmosphere is to shut ofl' from the earth's 

 surface a considerable portion of the sun's heat by absorbing it, tlie 

 capacity of the air to store heat and prevent its radiation into space 

 serves to make the earth habitable. Otherwise, the surface temperature^ 

 even under the tropics, wonld be lower than the lowest recorded degrees 

 of Arctic cold. Another effect of the selective absori^tion of the atmos- 

 jihere is to change the apparent color of the sun. In a transparent at- 

 mosphere the now golden sun would appear blue. 



Subsequently to this report, Professor Langley read a paper to the 

 Brit. Assoc. A. S., giving an outline of the results he has reached. It is 

 impossible to condense this paper, which is itself a highly condensed ac- 

 count of work extending over several years and covering a varied field. 



Solar parallax from observation of minor planets. — Mr. David Gill, 

 H. M. astronomer at the Royal Observatory, Cape of Good Hope, has 

 arranged with a number of observatories in both hemisi)heres for corres- 

 ponding observations of the minor planets Victoria and Sappho about 

 tlie time of their oppositions in the present year. . Victoria, in oppo- 

 sition on August 24, will be distant from the earth 0.89 of the earth's 

 mean distance from the sun ; and Sappho, which comes into opposition 

 in R. A. on SeiJtember 24, will be within 0.85 ; so that we have in each 

 case a favorable opportunity of applying the method of determining 

 the sun's parallax which was advocated and also api)lied by Professor 

 Galle, the director of the observatory at Breslau. In a communication 

 to the Astronomische N'acJirichten, Mr. Gill states that the necessary 

 extra-meridian observations will be made in the southern hemisphere 

 at the Cape, Natal, Melbourne, and Rio de Janeiro, and in the north- 

 ern hemisphere at Dunsink (Dublin), Strasbourg, Berlin, Bothkamp, 

 Leipsic, Upsala, Moscow, Clinton, U. S., and probably at Kiel. From 

 the clearer skies of the southern hemisphere, he believes that a fully corre- 

 sponding number of observations will be secured there, notwithstanding 

 the smaller number of observatories, and he invites co-operation from 

 other establishments in the northern hemisphere on this ground. A 

 list of the proposed stars of comparison is given in his letter. 



Maslielyne's value of the solar parallax. — Several inquiries have been 

 lately made with regard to the authenticity of a value of the sun's paral- 

 lax, attributed in many works to Maskelyne, the former Astronomer 

 Royal. These are answered as*follows in Nature : 



" This value (8". 723) was deduced by Maskelyne in an application of 

 ■what he calls a new method of determining the effect of i^arallax on 

 transits of the inferior planets, and is given in an article which ap- 

 pears to have communicated to Vince, Plumian Professor of Astronomy 



