10 SEVENTH REPORT—1837. 
of the force at any two stations, as the vibrations of the dipping- 
needle do of the total force. If, then, T is the time of hori- 
zontal vibration, and D the dip at a primary station, where the 
total force is taken as unity,—and if T’ and D! are the same 
quantities at another station, where I’ is the value of the total 
intensity derived by the vibrations of the dipping-needle,— 
cos D'! = T? .cos D 
i pa 
dip distinct from the ordinary method, and independent of the 
instrumental errors from which it is so difficult to clear the 
dipping-needle, especially one in which the poles are not re- 
versed in every observation. : 
Employing the observations at Melville Island, printed in 
the appendix to the account of that voyage, in this manner, 
we obtain the dip at Melville Island by the three horizontal 
needles as follows, viz. 
Needlebety:p0o% coc B8°4w 
Needle @ipa shies. A 88) 46 
Needle Sivas hes | «88 48 
The direct observation by the dipping-needle was 88° 43/°5. 
The following table exhibits the results of the observations 
of intensity in the two north polar voyages above noticed, cor- 
rected for temperature and arc, and expressed in terms of the 
general scale. 
; and we thus get a determination of the 
Time of Vibration. 
Station Latitude. | Long. | Therm Gidea lta Intensity. 
ee 
London, 1818 ......... age ati 480 | 472-0 
London, 1819 ....... me js 31 |359 52} 48 Fe 473°5 1:372 
London, 1820 ......... 480 472°9 
Shetland, 1818......... 60 09 |3858 48} 44 470 461°7 1-434 
MONPECENcotessaniccstcee 68 22 |306 10} 34 440 432°1 1°643 
Hare Island ............ 70 26 |305 08} 34 443 434°9 1:622 
One sasscdecccessteenss 75 05 |299 37] 33 447°2 | 439-4 1-590 
Ole Ce live cae stectocar sess 75 51 |296 54) 33 443°6 | 435°6 1-618 
MCR settee sates 76 45 |284 00} 33 435°0 | 429-1 1°666 
OM MCE ots conacevacess 76 08 |281 39} 33 436°0 | 430:0 1:659 
Once sate tssc. ccf desk 70 35 {293 05) 33 436:0 | 429-7 1:661 
On Ice, 1819.........00. 64 00 |298 10} 32 437°4 | 435°0 1:621 
Possession Bay .......+. 73 31 |282 38] 40 439°5 |432°9 | 1-637 
Regent’s Inlet ......... 72 45 |270 19} 32 439°0 |428:9 | 1-668 
Byam Martin’s Island.| 75 10 |256 16] 32 442°5 |430°'7 | 1:653 
Melville Island ......... 74 27 |248 18} 20 444°3 | 434°6 1:624 
Winter Harbour ...... 74 47 |249 12) 43 446°2 |4382°6 | 1-638 
Hansteen, 1819-1825.—In 1819 M. Hansteen, having com- 
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