Description of the Tables. Ixi 



100. A copper stove occupied tlie position S in the plan (Plate I.), and was 

 lighted every day from January 1 till March 15, 1843, with one exception, namely, 

 on January 23. It was only lighted three times again in 1843, namely, on Octo- 

 ber 19, November 25, and December 21, as it tended to increase the diurnal range 

 of temperature, and to create aerial currents within the Observatory. 



A small brick building was erected 24 yards to the east of the Observatory, 

 which was occupied after March 16 as a computing room. It was determined that 

 the bricks at that distance had no effect on the reading of the declinometer. 



§ 15. Description of the Tables of Observations. 



Daily Observations of Magnetometers, pages 1 — 28. 



101. The first column contains the Gottingen mean time, astronomical reckoning, 

 of the observations of the declination magnetometer. Gottingen time is 49™ 50® in 

 advance of Makerstoun time. 



The second column gives the absolute westerly declination in degrees, minutes, 

 ' and decimals, deduced as described, No. 23. 



The third column contains the observations of the bifilar magnetometer in scale 

 divisions, corrected for temperature to 26° Fahr., see Nos. 39 and 45 ; increasing 

 numbers indicate increasing force. The bifilar is observed 2"" after the declination. 



The fourth column contains the temperature of the bifilar magnet in degrees 

 of Fahrenheit. 



The fifth column gives the readings of the balance magnetometer in microme- 

 ter divisions, corrected for temperature to 26° Fahr., see No. 58 ; increasing num- 

 bers indicate increasing force. The balance is observed 3™ after the declination. 



The sixth column contains the temperature of the balance needle in degrees of 

 Fahrenheit. 



102. At the foot of each page are given the declinometer torsion-circle readings 

 for the torsion eliminated. A comparison of any one reading with the previous read- 

 ing will give the number of degrees of torsion introduced between the two periods ; 

 10° of torsion introduces an error into the observations of 0'*9 ; references are made 

 to footnotes, which at times indicate the cause that has produced the torsion, and 

 the period that it may have existed. The value, k, of one scale division of the 

 bifilar magnetometer, the whole horizontal force at Makerstoun being unity, is also 

 given, together with the approximate value, Jc, of one micrometer division of the 

 balance magnetometer, the whole vertical force being unity, obtained as in No. 55. 

 The value used in the abstracts differs considerably, and is A; = 0*000009. 



The observer's initial will be found at the same date of the meteorological ob- 

 servations. 



MAG. AND met. OBS. 1843. Q 



