so Land Magnetic Observations, 1905-10 



Lloyd-Creak Dover circle i8g continued. 



for the station at Spectacle Island, Bermuda; fuller information regarding the adopted 

 corrections of the needles of 189 will be given in the report of the vessel's work. The 

 tabular designation is iSg-g-io. 



The adopted correction of declination values with the compass attachment is +8'. 5 for 

 observations prior to July 1909, the mark being sighted with the peep sights; subsequent 

 to overhauling of the instrument in 1909 the correction adopted is +6' again for the 

 peep sights. 

 Dover circle 201. Type (a) ; the property of the Department. It was used during 1909 in Canada 

 and subsequently has been a part of the land instrumental outfit of the Carnegie. This 

 circle has been very satisfactory and the corrections of the dip needles have been well 

 determined by means of extensive comparisons with earth inductor No. 2, also aboard the 

 Carnegie; the following formulae have been adopted : 



Needle No. i FAI = o'.4 + o'.9 cos I o'.3 sin / 

 Needle No. 2 FAI = i .9 + 2 .6 cos / + o .4 sin / 

 Mean, Nos. i and 2 FAI = i .2 + i .7 cos / 

 The tabular designation is 201 12. 



The adopted correction of declinations observed with compass attachment is 4'. 6. 

 Dover circle 202.- Type (a); the property of the Department. It was used in Canada in 1909 

 and since then in Asiatic Turkey, Arabia, and Egypt. The corrections adopted from 

 special experimental observations and from comparisons with earth inductors are: 



The tabular designation is 202- 1256. 



The adopted correction of declinations observed with the compass attachment is : for work 

 prior to August, 1910, +9'.5, and subsequently, 7'.5. 



Lloyd-Creak Dover circle 203. Type (6) as modified; the property of the Department. It has 

 been a part of the Carnegie equipment as a reserve instrument. It has been used at only 

 a few auxiliary land stations; the corrections adopted for these from intercomparisons with 

 earth inductor 2 and circle 201 are: mean of needles No. 9 and No. 10 at the dip 67 north, 

 6'. 9; at the dip 54 north, 4'. 6 (needle No. 5, s'.o). The tabular designation is 

 203 9- 10. 



Dover circle 206. Type (a); the property of the Department. It was used in the United States 

 in 1910, and since in China. The corrections adopted from earth inductor comparisons 

 and needle differences for the dip 70 north are: mean needles Nos. i and 2, o'.7! rnean 

 needles Nos. 5 and 6, 2'. 2. The tabular designation is 206' 1256. 



The adopted correction of observed declinations ivith the compass attachment is +o'.4. 



Tesdorpf circle 2025. Type {d); the property of the Samoan Observatory; loaned the Department 

 for work in Polynesia during 1906. The correction adopted for the range of dip covered, 

 from comparisons at Apia and Christchurch, is: mean of needles Nos. 17 and 19, I'.o. 

 The tabular designation is 25-79. 



Casella circle 4655. Type (a) ; the property of the United States Coast and Geodetic Survey. It 

 was used by the Department only at one station in the United States. The correction 

 adopted for the mean of needles Nos. 3 and 4 is o'.o. The tabular designation is 4655-34. 



Earth Inductor Corrections to Standard. 



Earth inductor 48. This earth inductor is of the Wild type as made by Schulze, and is the property 

 of the Department. The adopted correction is o'.5. The tabular designation is EI 48. 



Earth inductor 2. Same type as No. 48, except for some minor mechanical modifications; made by 

 Toepfer and Son; the property of the Department. The correction to standard is o'.5. 

 The tabular designation is EI 2. 



