Ixiv Introduction to the Makerstoun Observations, 1844. 



The fourth cohimn contains the tem])eratnre of the bifilar magnet in degrees of 



Fahrenheit. 



The fifth cohimn gives the readings of the balance magnetometer in micrometer 

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

 indicate increasing 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 k of one scale division of 

 the bifilar magnetometer, the whole horizontal component being unity (see No. 38), 

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

 whole vertical component being unity, are also given ; the value of the latter given 

 here, 0-0000085, was deduced from observations made in 1846 (see No. 59), and is 

 erroneous, the true value is t=0-000010 (see Nos. 58 and 59) ; this value has been 

 used in the abstracts of results. 



108. Term-Day Observations of Magnetometers, pages 72-89. 



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 second and third columns contain the bifilar and balance magnetometer 

 readings, 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 temjieraturc 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, pages 92-157. 



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 Aurora boreales observed are given, with the times of the phenomena in 

 Gottingen mean time. 



110. Observations of Magnetic Dip, and fm- the Absolute Horizontal Intensity. 

 See Nos. 19, &c., and 84. 



111. Hourly Meteorological Observations, pages 172-308. 



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 



