590 



EXPEDITION TO POINT HAUHOW, ALASKA. 



DETERMINATION* Of THE MOMENT OF MASH (Mi) OF THE MASS KING ACCOMl'.l.\ Yl.\<: TllEODO- 



LITE MAGNETOMETER NO. 11. 



The mass ring aocompauyiug theodolite magnetometer No. 11 is of brass or gun metal, and 

 has no distinguishing mark on it. Its weight was determined at the Coast and Geodetic Survey 

 Office, by E. B. Lefavonr, April 29, 1881, and found to be 300.767 grains. 



The following measurements to determine the inner and outer diameters were made at the 

 Coast and Geodetic Survey Office by Assistant O. A. Schott: 



1881, April 20. Temp. 77 F. 



Outer diameter. Inner diameter. 



3.778<- 

 .778 

 .780 

 .780 



3.779 



2. 95' 

 2. 954 

 2.952 



J. !).-_' 



2.953 



1881, April 30. Temp. 73 F. 

 Outer diameter. Inner diameter. 



1. 489 

 .489 



.490 

 .400 



1. 4895 



1. 160'" 

 .159 

 .161 

 .160 



1.1600 



Thickness of ring=0. 529""=0. 208'" 



3. 779""=1. 4878'" 



Outer iliaim'tr=l. 4886 



2. 953= 1.1626" 



1.1000 



Inner diaineter=l. 1613 



'. 1100.767 



C ' 



(.74431-^0.55398 



0.89119 

 U i at 75 Fah. =0.93070 



0.89119 a. 94!W 



300. 767 2. 478L>3 



288 (ar. i-o.) 7. f.4li1 



MOMENT OF M.ISf! (M,) OF THE .l/.KSX A'/.W; K'l'dM l'.1.\yi Ml THKOIHIL1TK MAGNETOMETER NO. 11. 



M { =0.03070 at 75 Fall. 

 MI at any temperatnre t will be 



0.93070 [l+.00002(*-75)] 



I 



COMPUTATION OF THE MOMENT OF MASS (AI) OF THE LONG MAGNET L,, ACCOMPANYING THR 



TIIKODOLITE MAGNETOMKTKU .\Y. 11. 



[Station, Maj;utic Oliwrvatur.v, Waskiugtou, I>. 0. Observer. M. Smith. Dale, Juno 10, 1861.] 



