128 



MEMOIRS or THE NATIONAL ACADEMY OF SCIENCES. 



with tlic inicrometer thread, two of these nights were not satisfactory, and observations on one or 

 two of tlie others were inuch interrupted by doiids. It was found that on account of the nature of 

 the climate several spider threads, although tight when put in, hecame quite slack soon afterwards. 

 Tiie atniosidiere was very moist at night, and during the day the beat was excessive in the 

 transit tent. After trying with unsatisfactory results several spider threads brought along with 

 us, and two parallel fine copper wires, which were unsatisfactory for other reasons, it was thought 

 that perhaps a spider thread found on the island would be less aflected by climatic influences 

 than those previously tried. Accordingly one was found and put in. It was rather coarse, very 

 strong, and capable of being stretched tightly, and this one lasted during all the remaining observa- 

 tions. M. Palisa, of the European Expedition, gave up his diaphragm of spider lines and substi- 

 tnted a glass one in its place. 



The resulting value of the latitude deduced from four nights observations and 16 pairs is 10° 

 00' 1".C. This value may be changed slightly by the final reduction of all the pairs with 

 somewhat improved star places. The following is a specimen of the reduction of 1 pair observed 

 on four nights : 



United Staics Coast Survey. Latitude Computation. 

 [Latitude station : Caroline Islautl. Instrument: Transit telescope No. 2, with latituile level.] 



Date. 



Star. 



No. 



April 29" 



May 4 t . . 

 May 7 t . . 

 May 8t.- 



Mean. 



269 



277 



Micrometer. 



Kead- 

 ing. 



T. D. 



30 39. 5 



11 79.0 

 33 84.0, 

 15 34. 5' 



31 3.5.51 



12 91.0, 



32 75. Ol 



14 11. o; 



Diff. 

 Z. D. 



T. B. 



18 60. 5 

 18 49. 5 

 18 44.5 

 18 64.0 



T.evel. 



N. 



13.0 

 10.5 



12.0 



7.0 



Diflf. 



N— S, 



Declination. 



7. 10. 

 10. 0! 6.0 



7.811.0 

 10. Ol 9.0i 

 14.5' 3.11 



.5.011.21 



+14 18 

 +4. 5 —34 4 



Snm and 

 half sum. 



Corrections. 



Microm. Level. Eefr, 



-1-1.0 

 —2.2 

 +5.2 



6. 90 —19 46 35. 95! 

 42.15'— 9 53 17.62—6 44.08+1.96 

 34.88 



17.44—6 41.711+0.44 

 34.49 



17.25—6 40.62 

 34. 35 

 17.17—6 44. 



7.70| 

 42. .58 



8. 30l 

 42. 79 



8.51 

 42. 86 



—0.96 



+2.27 



—0.13 

 0.13 

 0.13 



—0.13 



Latitude. 



-9 59 .59. 87 

 58.84 

 58.96 

 59.89 



-9 59 59. 39 



* E. D. P., observer. 



tS. J. B., observer. 



Declination. 



One revolution of micrometer — 43. 44 



One revolution of latitude level = 1-75 



