2 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



lent by the Observatory to various astronomers, who sub- 

 mitted reports of the work done. The excellent results 

 reached have been a gratifying proof of the heartiness of the 

 co-operation on both sides. 



The detailed account of these results is given in the sec- 

 tions on Solar Eclipses and on the Transit of Mercury. These 

 and other subjects are spoken of briefly under their appro- 

 priate heads. It must be remembered that the accounts here 

 given are necessarily the barest summaries, and are intended 

 mainly to call attention to work which has been done, in or- 

 der that a reference may be made to the original sources if 

 desired. At the same time, it is clearly impossible to give 

 references to all the memoirs consulted. For such biblio- 

 graphical information the reader is referred to Darboux et 

 IIoueTs Bulletin des Sciences Matliematiques et Astrono- 

 miques (monthly, Paris), to Nature (weekly, London), to the 

 Observatory (monthly, London), and other journals. Free 

 use has been made of reviews by writers in these and other 

 periodicals. 



An important feature of the Astronomical Summary for 

 1877-78 are the reports from American observatories (p. 46), 

 furnished by the directors themselves in answer to a circu- 

 lar letter. It is hoped that by means of these replies accu- 

 rate knowledge of the activity of our observatories may be 

 had, and it is intended to continue these in the future. A 

 similar series of reports for European observatories is yearly 

 made to the German Astronomical Society. These have been 

 translated and condensed, and are given here (p. 76). 



An abstract of an official report on the observatories of 

 Italy, by M. Rayet (of the Observatory of Marseilles), is also 

 given (p. 76). 



The various important communications of Professor Wat- 

 son on the subject of the discovery of Vulcan are given un- 

 der that head ins:. 



NEBULA AND CLUSTERS; NEBULAR HYPOTHESIS; CON- 

 STRUCTION OF THE HEAVENS. 



In the journal of the Italian Spectroscopic Society for No- 

 vember, 1877, Professor Celoria has a paper on the general 

 distribution of the stars in space. In this paper he combines 

 the gauges of Herschel, the results of the Durchmusterung 



