Obseevations of Magnetic Dip, Maech 18— July 8. 1842. 



63 



Gottingen 



Mean Time, 



Commencement of 



Observations. 



Dura- 

 tion 

 of 

 Obser- 

 vation. 



Thermo- 

 meter. 



No. 



of 



Needle. 



Mean of Readings. 



End A. 

 North, 



End B. 



North. 



A. North 

 Minus 



B. North. 



Observed 

 Dip. 



Remarks. 



d. h. m. 



Mar. 18 5 25 



Mar. 21 20 30 



Mar. 25 5 5 



Mar. 28 20 20 



Apr. 1 5 20 



Apr. 4 20 45 



Apr. 8 5 30 



Apr. II 20 45 



Apr. 15 6 



Apr. 18 20 10 



Apr. 22 5 20 



Apr. 25 20 20 



Apr. 29 5 25 



5 40 



20 20 



,iMay 13 6 20 



|May 16 20 10 



|May 20 5 20 



May 23 21 45 



May 30 20 15 



June 6 20 45 

 June 10 5 15 



June 13 21 30 



5 20 



June 20 20 15 

 June 24 5 35 

 June 27 20 25 

 July 1 

 July 4 

 July 8 



5 



21 



7 



65 



160 



100 



85 



55 

 85 

 60 

 90 



5 15 120 



120 

 90 



75 



100 



85 

 105 

 70 

 85 

 85 

 120 



48-0 

 450 

 550 

 450 

 490 

 44-0 

 55-0 

 42-0 

 47-0 



620 

 49-0 



61-4 

 570 



47-2 



63-1 



55-0 

 57-0 

 55-0 

 55-5 



69-0 



59-5 

 65-6 



650 



61-0 



600 

 65-5 

 560 

 67-3 

 60-5 

 61-7 



il 



71 

 71 

 71 

 71 

 71 

 71 

 71 

 71 

 71 

 71 



27-37 

 30-12 

 30-12 

 29-25 

 29-37 

 28-62 

 24-50 

 28-87 

 24-37 

 26-12 



71 28-00 



71 30-00 



71 24-62 



71 28-12 



71 32-37 



71 28-25 



71 23-87 



71 29-50 



71 21-87 



71 31-12 



71 25-87 



71 31-75 



71 30-25 



71 37-88 

 71 32-88 



71 32-62 



71 33-12 



71 

 71 

 71 

 71 

 71 

 71 



38-00 

 33-88 

 38-50 

 36-00 

 40-38 

 38-50 



71 

 71 

 71 

 71 

 71 

 71 

 71 

 71 

 71 

 71 



1800 

 21-12 

 9-87 

 11-37 

 21-87 

 27-37 

 18-75 

 23-87 

 25-37 

 20-87 



71 32-62 



71 34-87 



71 24-87 



71 19-62 



71 25-87 



71 18-37 



71 17-25 



71 25-62 



71 24-87 



71 1500 



71 16-12 



71 15-62 



71 15-50 



71 12-00 

 71 8-75 



71 16-12 



71 14-00 



71 

 71 

 71 

 71 

 71 

 71 



7-88 

 12-50 

 12-75 

 12-37 

 16-12 

 15-00 



+ 9-37 

 + 9-00 

 + 20-25 

 + 17-88 

 + 7-50 

 + 1-25 

 + 5-75 

 + 5-00 

 - 1-00 

 5-25 



+ 



- 4-62 



4-87 



0-25 



+ 8-50 



+ 6-50 



+ 9-88 



+ 6-62 

 + 3-88 

 - 3-00 

 + 16-12 



+ 9-75 

 + 16-13 

 + 14-75 



+ 25-88 

 + 24-13 



+ 16-50 



+ 19-12 



+ 30-12 

 + 21-38 

 + 25-75 

 + 23-63 

 + 24-26 

 + 23-50 



71 

 71 

 71 

 71 

 71 

 71 

 71 

 71 

 71 

 71 



22-69 

 25-62 

 20-00 

 20-31 

 25-62 

 28-00 

 21-62 

 26-37 

 24-87 

 23-50 



71 30-31 



71 32-44 



71 24-75 



71 23-89 



71 29-12 



71 23-31 



71 20-56 



71 27-56 



71 23-37 



71 23-06 



71 20-37 



71 23-69 



71 22-87 



71 24-94 

 71 20-81 



71 24-37 



71 23-56 



71 

 71 

 71 

 71 

 71 

 71 



22-94 

 23-19 

 25-56 

 24-19 

 28-25 

 26-75 



This and the previous observations, with the 

 exceptions noted, were made by Mr. Russell. 

 (This and the following observations were 

 I made by me. J. A. B. 

 It is possible that in some of the readings for 

 this observation the divisions of the limb 

 had been taken for 5' instead of 10'. 

 ^Levelled the agate planes, care being taken 

 } that the glass door was shut, as in shutting it 

 ( exerts a pressure on the bottom of the box. 

 Although great care and much time was 

 bestowed on this observation, it can hardly 

 be considered good, very different readings 

 being obtained after repeatedly lifting the 

 needle on the Y's. 

 Level of agate planes verified. 

 In this observation the needle was placed 

 carefully on the agates, lifted by the Y's, 

 gently let down and allowed to vibrate 

 through about 10° ; then, when at rest, read. 

 This observation made in the same way as last. 

 Level of agates verified. 



The observations of June ?>^ were made in 

 order to determine the efifect, on the final 

 result, of lifting the needle on the Y's one, 



I two, or three times. See Note below. 

 While changing the poles the needle fell upon 

 the carpet from a height of about two feet. 

 J This result obtained in the same way as the 

 \ second result, June 3''. 

 Id. 



In some of the readings the needle had to be 

 lifted frequently before a satisfactory obser- 

 vation could be made. 

 Allowing the needle to vibrate through 10° 

 has not been fovmd satisfactory. The needle 

 is now checked near its supposed position of 

 rest, and is lifted and lowered by the Y's 

 tiU satisfied that lifting does not alter the 

 reading. 



Great care taken with this observation. 



June Z'^. The needle was checked so as to allow it, when lowered on the agates, to vibrate through 10°. After coming to rest the position 

 was read. The first result, .June S^, was obtained from the readings made in this way. After each of the readings for the first result, the needle 

 was lifted by the Y's and lowered gently (the arc of vibration being small) and again read ; — these readings give the second result. The needle 

 being lifted, &c., as in the second case, a third result was obtained. 



