Ixii Inteoduction to the Makerstoun Obseevations, 1845 and 1846. 



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 micrometer 

 divisions, corrected for temperature to 26° Fahr. (see No. 79) ; increasing numbers 

 indicate increasinsr force. The balance is observed 3" after the declination. 



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

 Fahrenheit. 



The seventh column contains the observer's initial (see No. 5). 



At the foot of each page the time is given during which the declination mag- 

 net has remained untouched, or the amount of torsion found in the suspension thread 

 when that has been determined (see No. 12). The value, A;, of one scale division of 

 the bifilar magnetometer, the whole horizontal component being unity (see No. 40), 

 and the value, h, of one micrometer division of the balance magnetometer, the 

 whole vertical component being unity (see No. 60), are also given. 



108. Term-Day Observations of Magnetometers^ 1845, pages 72-87. 



The first column contains the minute of Gottingen mean time of the declina- 

 tion observations, the hour being given in the middle of each triplet of columns. 

 The first column of each triplet contains the absolute westerly declination ; the 

 second and third columns contain the bifilar and balance magnetometer i*eadings, 

 reduced to the temperature of 26° Fahr., as in the hourly observations. The 

 temperatures of the magnets at the commencement of each hour will be found 

 with the hourly observations, and the observer's initial for each hour are in the same 

 place. The corrections for temperature are applied to the observations in the fol- 

 lowing manner : — The correction to the first observation of each hour being applied 

 for the known temperature of each magnet, the temperature is supposed to change 

 uniformly throughout the hour, and the corrections for the intermediate observations 

 are interpolated between the initial corrections. 



109. Extra Observations of Magnetometers^ 1845 and 1846, pages 90-117 and 

 326-341. 



These observations are made generally during magnetic disturbances. The 

 same remarks apply with reference to temperature corrections, &c., as for the term- 

 day observations, excepting that the Gottingen day and hour are given in the first 

 column, and the minute is given for the observations of each instrument. Notes 

 upon the Aurorse boreales observed are given, with the times of the phenomena in 

 Gottingen mean time, pages 118-127 and 342-343. 



110. Observations of Magnetic Dip, and foi' the Absolute Horizontal Intensity. 

 See Nos. 19, &c., 82, and Addendum to Introduction. 



111. Hourly a.nd .Daily Meteorological Observations, 1845 and 1846, pages 136- 

 272 and 354-409. 



The first column contains the day and hour, Gottingen mean time, of the obser- 

 vations, all of which are made within a few minutes of the hour, and generally in 



