EEPORT OF THE SECRETARY. 25 



were also noted by Mr. Raymond, who had been charged with the 

 meteorological observations. The total eclipse lasted 60^ seconds. 

 A corona light appeared at the same time as the solar clouds, extend- 

 ing from the sun farthest in radial lines drawn from the centre, and 

 passing through the clouds, but was nowhere traceable more than 15' 

 or 16' from the solar disk. There was no appearance of fasces or 

 bundles of rays, but only a uniformly diminishing and slightly orange 

 tinted light, whose brightness and extent were apparently influenced 

 by the film of mist. It vanished with the first appearance of the sun. 



As already stated. Lieutenant Gilliss was accompanied by Mr. Car- 

 rington H. Raymond, of New York, who rendered him essential 

 assistance during the whole expedition, as well as at the time of the 

 eclipse. 



The communication of Lieutenant Gilliss will be accompanied by a 

 drawing of the appearance of the eclipse at the time of greatest obscu- 

 ration, and will form a part of the eleventh volume of the Smith- 

 sonian Contributions. 



5. The investigations of Mr. Meech relative to the heat and light of 

 the sun have been continued during the past year and are still in 

 progress. The memoir containing the result of these investigations 

 obtained previous to September, 1855, was published as a part of the 

 ninth volume of the Smithsonian Contributions, and has received the 

 approbation of the scientific world. It is noticed with credit to the 

 Institution in the proceedings of the Astronomical Society of London, 

 and in a letter on the subject from Sir John Herschel. 



The memoir already published contains a discussion of solar heat 

 in all its astronomic phases at the exterior of the earth's atmosphere. 

 The labors of Mr. Meech have since been directed to the partial 

 absorption or extinction which the rays experience in passing through 

 the atmosphere to the earth's surface. The phenomenon is one of 

 special interest, and various instruments have been devised for its 

 measurement ; among which the pyrheliometer of Pouillet, and the 

 actinometer of Herschel, may be mentioned. The observations with 

 these instruments, says Mr. Meech, are certainly valuable and in- 

 structive, but, with one very doubtful exception, they fail to exhibit 

 any distinct law. The law of absorption not being obvious directly 

 from observation, the simjjle hypothesis has generally been adopted 

 that equal thicknesses or strata of the medium absorb equal pro- 

 portions of the light or heat incident upon each stratum. Lambert, 

 Laplace, Pouillet, and others, have expressed this assumption in an 



