H'lJIory of AJlronomy for 1798. 25 



On the 20th of June the Inftitute decreed the prize for 

 time-keepers, ufed in afcertaining tl>e ionguudc at fea, to 

 two chronometers made by C. Louis Berthoud, the going of 

 which was obferved by C. Meffier and myfelF during fix 

 months. I carried one of them to Gotha; and I had the 

 fatisfaAion of finding that a journey of two hundred leagues, 

 in a carriage, did not make the change of a fecond per day 

 in its movement. Tlie Inftitute will propofe, on the 4th of 

 January, as the fubjeft of a prize to be adjudged in two 

 years, the theory of the comet of 1770, which was propofed 

 by the Academy in 1792. It has not hitherto been poflible 

 to calculate this comet but in an orbit of five years, and a 

 revolution fo {hort is improbable. 



The Mcmous of the InjVilute for the Year IV. have ap- 

 peared. They contain my Theory of Mercury, the rcfiilt 

 of forty years refearches. This was the firft memoir read 

 in the firlt fitting of the firft clafs of the Inftitute, on the ift 

 of January 1796. 



The Bureau des Longitudes has publiflied two volumes of 

 the Connolffcmce des Terns for the years VI 11. and IX., the 

 additions to which were edited under my infpeftion. It has 

 determined that this work, in future, fliall contain 500 page?, 

 in order that we may infert in it our obfcrvations and calcu- 

 lations. Thefe two volumes contain a number of important 

 articles : new catalogues of the ftars ; tables of the moon's 

 horary motion by Delambre ; obfcrvations of Mercury by 

 \'ldal, the great and aftonifliing obferver of that planet, to 

 whom wc are indebted for being able to lay that the obfcr- 

 vations of Mercury, fo rare and fo difficult before his time, 

 are at prefent as numerous as thofe of the other planets, and 

 leave nothing more to be wiflied for on that head. He has 

 alone done more than all the other aftronomers of the world, 

 either ancient or modern ; and we may now difpenfe with 

 cmploving our attention on that fubjeft. C. Vidal mufl: 

 make every other aflronomer dcfpair of exceeding him, 



h All 



