578 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



feebly ■witli less lime than is required to form a hydrate of one to one, the 

 weaker compound being probably two of lime to one of water. 



SiRius AND Its Companion. 



The light of Sirius, according to the calculations of Sir John Herschel, is 

 224 times greater than that of the sun, its parallax being 23-lOOths of a 

 second, its distance from the earth is 52,000,000,000,000 of leagues, and 

 its light is about twenty-two years in reaching us. 



Some irregularity in its motions have induced the suggestion that it was 

 influenced by a star companion. Such a star was discovered by Alvah' 

 Clark, the celebrated optician and observer of Cambridge, Mass., January 

 31, 1 862. The January^number of The Edinburgh New Philosophical Journal 

 for 1864, contains an interesting communication from Mr. T. H. Saiford, as- 

 sistant at the observatory of Harvard College, in relations to the motions 

 of the companion of Sirius, in which the observations of Bond of Cam- 

 bridge, Rutherford of New York, and several European astronomers are 

 cited, in relation to the queries whether the new star is unconnected with 

 Sirius, or a satellite, or the disturbing body. He thus concludes : "It is 

 consequently highly probable that the disturbing body has actually been 

 found; that what was predicted by theory has been confirmed by sight. 

 The importance of continued observations cannot be too highly felt. The 

 companion of Sirius must be measured for the coming year, and for 

 several years, while Sirius itself should be re-observed with meridian in- 

 struments." 



A New Developer. 



At the February meeting of the American Photographical Society, held 

 at the New York University, Mr. Duchochois described his new developer, 

 which consists in combining constituents previously used in photography 

 in the following manner : Sulphate of the protoxide of iron, 480 grains; 

 water, 17 fluid ounces. After complete solution a drachm of aqua ammonia 

 fortis is added. By decomposition a double sulphate is formed, oxyde of 

 iron is precipitated, and afterward converted into acetate by addition of 

 acetic acid in excess (three fluid ounces No. 8). The collodion must be 

 that which gives little intensity and great sensitiveness, and the other 

 materials used be absolutely pure to avoid fogging. Under these con- 

 ditions the most perfect negatives, are obtained in a time excessively 

 shortened. 



Mr. Crum, a practical photographer, presented fine pictures made with 

 the new developer, and stated that the time of exposure was sho rtened one- 

 half 



Paper Negatives. 



At the same meeting Mr. H. J. Newton exhibited specimens of paper 

 negatives, prepared by him with gum benzoin dissolved in alcohol. By 

 Mr. Newton's Drocess the grain of the paper is no longer visible. Photo- 

 graphs made from these negatives, were also exhibited and greatly ad- 

 mired. 



Tide Waves and Wind Waves. 

 The regular subject for discussion, " Wave and Tidal Movements," and 



