170 DOOLITTLE—ORBIT OF DOUBLE STAR JS 518. _ [April3, 
of the American Philosophical Society because it had chosen 
Franklin for its President, and that Richard Penn had been 
Lieutenant Governor (as Deputy for that uncle and his brother) 
from 1771 to 1773, it must have been difficult for Franklin not to 
feel that such a letter from such a man was indeed a tribute to his 
position, achieved solely by his own efforts. 
From this mass of correspondence, I have selected some letters 
showing the state of public opinion in New England in 1774, 
and from London in 1775, including a characteristic letter from 
Priestley and from Charles Lee and Wayne in the field. Much 
more might be printed to show how well Franklin kept in touch 
with all that was of interest during his long and busy career. It is 
well that this venerable Society, so largely the result of his labors, 
should be made the custodian of the papers that follow almost his 
daily thoughts, and it is to be hoped that the preparation and pub- 
lication of a Calendar showing their contents may be completed 
at no distant day, certainly by the two hundredth anniversary of 
the birth of our founder, and thus perpetuate his memory. 
Franklin’s legacy to the Philosophical Society was ninety-one 
volumes of the Astory of the Royal Academy of Sciences at Paris, 
thus helping that collection of publications of scientific societies 
that make so valuable a portion of its Library. 
THE ORBIT OF THE DOUBLE STAR 2 518. 
BY ERIC DOOLITTLE. 
(Read April 3, 1903.) 
INTRODUCTION. 
It is well known to astronomers that many of the stars of the 
sky which to the naked eye appear to be but single stars are when 
viewed with the telescope seen to be made up of two or more stars 
very close together. About twenty thousand such double stars 
have been measured and catalogued, and the number is continually 
being added to through the discoveries of the great modern tele- 
scopes. There are scarcely fifty of these, however, of which a 
determination of the orbit is possible. 
It was in the years 1802 and 1803 that the classic memoirs of 
Herschel appeared, in which it was shown for the first time that 
pissin, Mew 
