Prench Board of Longitude. i8l 



of the military and naval expeditions undertaken by the 

 Swedes about the middle of the twelfth centur)'. The prize 

 is a gold medal of the value of fifteen ducats. 



Infcriptions and Devices. — I. A Latin infcription for the 

 Exchange at Stockholm. 2. Plan of a medal to comme- 

 morate the moft remarkable events which have taken place 

 in Sweden in the courfe of the prefent century. The prize 

 is a sold medal of the value of twelve ducats. 



o 



The papers, &c. of the competitors piuft be tranfmitted to 

 the Academy, in the ufual form, before the soth of Ja- 

 puary 1801. 



FRENCH BOARD OF LONGITUDF,. 



The following paper has lately been publidied, figned by 

 Delambre the prefident, and Lalande the fecretary, of the 

 French Board of Longitude : 



The tables of the moon are of equal importance to aftro- 

 nomy and to navigation : the moft celebrated geometricians 

 have exerted themfelves to illuftrate the theory on which 

 thefc tables are founded. The moil afliduous labour of 

 artronomy is, to obferve with care all the movements of this 

 planet, without which there would be no real geography, 

 and which furnifli the navigator with the mofl infallible 

 means of afcertaining the pofition of his- vefTel, of direiling 

 its courfe, and of arriving in fafety at any determined point 

 of the globe. In proportion as the Newtonian theory was 

 thoroughly examined and underftood, and as aflronomical 

 inftrumenls and modes of obfervation were improved, the 

 lunar tables were improved alfo. Mayer, uniting his own 

 obfervations to thofe of cotemporary geometricians, and fe- 

 lefting the mofl accurate obfervations, was enabled to com- 

 pofe tables, which having been fince compared with nearly 

 twelve hundred unpublifhed obfervations, have been found 

 wonderfully accurate, Maron, under the dircftion of Dr. 

 Mafkelyn, made a new improvement in them by addint* 

 feveral equations which had been omitted but pointed out 

 by Mayer, and by modifying the co-efficients of all the refl* 



But, notwithlfanding this care, thele tables, fo valuable 

 towards the middle of the century, began to lofe progref- 



fively 



