394. EL S. Holden—Measures of the Rings of Saturn. 
Washington measures of Belts on Saturn. 
Date, 1878. Wash. m. t. A B 
h m a 
Sept. 9 10 30 2°8 46 
17 10 40 2°4 5-2 
19 10 +50 2°8 51 
Oct.2 1 FEs30 2-4 5:2 
8 10 50 2°8 ve 
14 3: 30 2°2 571 
21 8 30 2°6 ips 
25 9. 38 2°6 4°7 
26 9.36 18 4°3 
Nov. 5 10 44 2°8 6°43 
N. B.--The measures in columns A and B are as follows: A=distances of the 
south pre of the bright equatorial belt of Seaagulal : southern hemisphere from the 
major axis of the ring; and B=distance of the center of the dark band in Saturn’s 
northern hemisphere from the major axis of the 
add here that I have as reduced the Washington 
aevascie of the position angle of the major axis of Saturn’s 
ring and determined the inclination of the plane of Saturn’s 
ring to the pines. of the orbit of Saturn. The observations 
were made on se Mhsodg nal nights in the years 1877, 1878 
and 1879 which were favorable for this purpose. The 26-inch 
equatorial, the filar parte tei and eye-pieces magnifying 
0 to 800 times, were employed. The reductions have 
been made by Bessel’s. rigorous formule given in his Abhand- 
lungen, vol. i, p. 321. The e quantity sought is 2’, which is the 
inclination of the plane of Saturn’s ring to the plane of Saturn’s 
orbit; the results are as follow: 
From the forty observations of Professor Hall we have for 
1877°948=1877, Dec. 11; #=26° 38’ 47’4-1"37. The probable 
error of a single observation i is +86. 
‘From the thirty-seven observations made by me we have for 
ou 771—1878, Oct, 8; = 26° 67) 2-169. The probable 
rror of a single obicr vation | is +103. 
eae twenty-two observations give 
1818°726=1818, Sept. 20; 7’=27° 0’ ; "4+:5'2. The probable error 
of a single observation was +24’ 
I have not combined the results eed by Professor Hall 
and myself since the observations of October 13, 14, — and 
of pieecwion 18, 14, 1878, show that they are not comparable. 
My observations agree with those of Bessel within the ute 
of the cictable errors. A comparison of the observations of 
Professor Hall with Bessel would indicate a diminution of the 
inclination since 1818. 
Washburn Observatory, University - Wisconsin, 
Madison, 1882, January 3 
