20 ANNUAL KECORD OF SCIENCE AND INDUSTRY. 



the solar rays, irrespectively of the duration of sunshine, and 

 of the angle at which the rays strike the ground. This 

 should be measured by the excess of the reading of the ther- 

 mometer, with blackened bulb, in vacuo, freely exposed to 

 sun and air, above the temperature of the air and shade. 

 The second is the total heating effect upon a large mass of 

 earth or water, also irrespective of the angle of the incidence 

 of the sun's rays, but depending both upon the intensity and 

 duration of the sunshine. This may be measured by insert- 

 ing a thermometer into the centre of a hollow sphere, such as 

 a sixty-eight-pound shell, which might be filled with water, 

 and should be elevated above the ground. The third is the 

 heating effect produced upon the earth's surface, depending 

 upon the altitude of the sun, as well as upon the intensity 

 and duration of sunshine, not to mention moisture, evapora- 

 tion, etc. This may be measured by a thermometer, not in 

 vacuo, placed upon the ground, or, still better, perhaps, by 

 one buried just below the surface of a level sand-bed." It is 

 to the first of these, viz., actinometry, that he had directed 

 attention ; and while not saying that the other investigations 

 are not equally important, he thinks it best not to obtain 

 figures which represent the action of a variety of causes, the 

 individual effect of which is unknown ; but of one cause only, 

 and afterward to proceed to the investigation of two or more 

 causes combined. Quar. Jburn. Meteor. /Soc, London, 2-27. 



THE SOLAR ECLIPSE OF 1870 IX ITALY. 



The report of the observations made by the Italian astron- 

 omers on the solar eclipse of December 22, 1870, has been re- 

 ceived in this country. It will be remembered that, in order 

 to assist in the observations of this important eclipse, Pro- 

 fessors Newcomb, Hall, Harkness, and Eastman were sent, at 

 the expense of the government, from the Naval Observatory 

 at Washington, to occupy proper stations in Spain and Sicily. 

 Their reports were promptly published hy our own govern- 

 ment. The Italian government, on the other hand, repre- 

 sented by the numerous astronomers of that nation, among 

 whom the names of Secchi, Donati, Denza, and Tacchini are 

 well known in America, occupied two stations, each manned, 

 as we may say, by six of the most experienced astronomers 

 of the nation, and by a number of assistants. The observa- 



