Addendum. 



Ixvii 



122, The following are the final results for all the bars operated on* : — 



Makerstoun 3-65-inch collimator named M, unmarked, 1st series, 6 determinations, 0"00390 



2d series, 4 0-00465 



3d series, 4 0-00403 



4thseries, 4 0-00397 



5thseries, 6 000435 



Mean of all determinations, 0-00417 



Prof. Bache's 3-65-inch collimator, named B, marked 4, series of 4 determinations, 0-00627 



Prof. FORBES's 3-65-incli solid bar, named F, unmarked, 0-00569 



123. In the observations for the temperature coefficients, the water was con- 

 tained in a small wooden vessel fixed upon the deflecting rod of the Makerstoun 

 theodolite (unifilar, or nine-inch circle) magnetometer ; the temperature was ob- 

 tained from two thermometers with bulbs of different dimensions, one placed at each 

 end of the immersed magnet, the mean of both indications being employed. The 

 following table contains the results for 5 bars : — 



Table 14. 



-Observations for the Temperature Coefficients of different Magnets, 

 September 8, 1847. 



Gott. 





Theemometers. 



Unifilar 



Declination 



Bifilar 



Unifilar 



Temperature 

 Coefficient. 



Mean 



Magnet. 







Scale 



Scale 



Corrected. 



Circle Reading 



Time. 





Jones. 



Ross. 



Reading. 



Reading. 





Reduced. 





h. m. 





o 



o 



So. Div. 



Sc. Div. 



So. Div. 



o 





1 



Away. 

 B. 4. 







182-42 



6-30 





236 54-79 

 192 54-47 





1 25 



89-6 



89-9 



200-20 



1-95 



557-7 



o 



6 6 6 

 o o o 

 o o o 

 o o o 



00 00 GO 

 to 00 00 



1 33 





64-1 



64-2 



193-65 



1-55 



560^1 



48-03 



1 39 





39-6 



37-4 



185-52 



2-22 



557-2 



39-25 



1 46 



2 3 





63-1 

 89-0 



633 

 89-0 



1.92-47 

 204-85 



2-55 

 2-60 



556-4 

 558-6 



46-15 

 58-80 



•000098 

 •000090 

 •000087 

 •000098 



2 8 





67-7 



67-4 



198-20 



2-67 



558-8 



5b93 



2 14 





39-0 



36-6 



190^10 



3-02 



559-7 



43-40 



2 19 





61-1 



60^4 



196^95 



3-00 



560-6 



50-43 



2 25 





92-2 



92^2 



207-05 



325 



560-9 



60-63 



5 6 



B.— 



90-9 



90^7 



227-87 



952 



567-8 



193 17-75 



0^000094 

 •000080 

 •000083 

 •000100 

 •000095 

 •000088 



5 11 





67-0 



67^3 



221-00 



9^77 



568-0 



10-53 



5 18 





40-6 



39-4 



214-05 



10-02 



567-6 



3-25 



5 24 





62-0 



61-4 



220-25 



9-97 



568-6 



9-63 



5 28 





88-7 



88-9 



229-30 



10-05 



569-3 



18-86 



5 35 





67-6 



67-3 



222-97 



10-22 



569-4 



12-25 



5 42 





40^5 



38-7 



215-00 



10-45 



568-8 



3-93 



6 



M. 



40^5 



39-9 



296-00 



10-77 



569-7 



194 26-73 



0-000098 

 -000110 

 -000103 

 •000094 



6 5 





65^1 



64-6 



304-15 



11-22 



570-8 



34-79 



6 10 





89-6 



89-6 



31155 



11-12 



568-8 



42^45 



6 16 





65^1 



63-9 



304-00 



11^20 



569-4 



34-65 



6 22 





38-4 



37-2 



297-50 



11^67 



571-4 



27-67 



6 34 



F. 



40^2 



38-8 



171-47 



12-17 



570-8 



192 18-15 



0^000295 

 -000316 



6 39 





64^9 



64-7 



195-75 



12-25 



570-5 



42-99 



6 44 





88-0 



88-5 



220-40 



12-20 



571-6 



68-29 



7 6 



I. 23. 



94-0 



94-3 



336-00 



11-87 



571-2 



194 66-99 



0-000200 

 •000184 



7 11 



67-9 



67-8 



320-05 



11^67 



571-4 



50-78 



7 16 



39-7 



38-0 1 



303-90 



11-62 



571-4 



34-26 



* Each determination, it will be seen from Table 13, commences with the deflecting bar having 

 the same end to the north ; this should have been avoided, since, in the event of increase of tempe- 



