CONTENTS. 
PAGE 
IntRopucTION— 
Position amd Description of the Observatory,+++++++.1.:++-ssseeeceeeeeseeseneencesuensccaensenseseaners ix 
System of Observation, and Staff of Observers, xi 
Declinometer— 
Deseription of the Declinometer, ---+---20sce...ctssc+esesccesscosccnsscotesscnsesccncerseecouce xii 
Values of the Scale Divisions, Geasasicaale culsnsnuaisescveses cevssucwededeae deviants dm acchasutcnie ces xiii 
Scale Readings for the Magnetic Axis, doulaatm stay aie owelusia ewelcisidieled’eiank'dawaakatccieaaekacee se Xiv 
Corrections, -..--.-+ wididaveis saslwuslsvinleae Sawielnneinielsivelsiels ce'siudels vcldevieweldwesiine recs teeciecsss ceettedes ta Xiv 
Removal of Torsion, &€., «-++++++sseeeeeeee Fore Neviedevivva cee seeeetisecsreseeiee eee uae xv 
Time of Vibration, --.-..-- xvi 
Method of Observation, Xvi 
Absolute Magnetic Declination, --.---....... = Xvi 
Unifilar Magnetometer and Observations of the Absolute Horizontal Intensity of the Earth's 
Magnetism— 
Position and Description of the Instrument, Seuiet wie oetiensaes'squ sas ppeisieiade¢-siacwsiea'v'sslseu X1x 
Formula of Reduction, methods of Observing, &¢., +++-::::ssseeessceseeeeeccecceeeteeeas Xx 
Results of Observations (see Addendum). 
Bifilar or Horizontal Force Magnetometer— 
Description of the Instrument, seninetrsieisleta(ciesivalssisisers'enis ue sacieceines = cpiee ace slananetaee nacre SATOOC XXV 
Usual formula of Reduction, XXVii 
New formula of Reduction, XXVii 
Determinations of the Coefficient of Reduction, oneenneusinelguSis|siaieasiaaa ture aaaacks mentions <a XXVill 
Coefficients applicable to the observations since 1841, XXXi 
Constants for Reduction after turning the Arms of the Torsion Circle, --+--.22ssee0es XXxxi 
Time of Vibration of the Bifilar ag BE CE 3 OND OSE BEET SO OSU CiLac ACCEL ABBE EEE a xxxiii 
Mode of Observation,.--...-+.-- XXxili 
Balance or Vertical Force Magnetometer— 
Description of the Instrument, spocboesenisas XXXxili 
Usual formula of Reduction pitt eee nc eee cweceavenssseeecsesenee be enes Been eeeersedneccccncescncccs XXXiV 
Times of Vibration, caainnsnot sane cee Regus apebe acsieersitsstsakesd teunasenedccceenetes awobeosapernene XXXV 
Conclusions from the observations of the Time of Vibration, ---.-.-...--.-- saeeeeceners XXXVi 
Observations to discover the causes of the anomalies in the Time of Vibration, ----  xxxvii 
Insufficiency of the usual formula, «--.-.-..++ einivioe(srate a netslncleinw'slaalipie sian teiesion tenets tceiee cee XXxix 
Observations for a statical determination of the Balance Coefficient, --. xl 
Adjustment of the Balance, and connection of the Observations, +++---++--.s0.-s0000-.. xlii 
Method of Observation, lanieaiale pie'els em abcnisisiatsiatie= Gs pica acta oes ee Reece Sanaa ake Wee No xliii 
The Temperature Coefficients of the Deflecting, Balance, and Bifilar Magnets— 
Temperature Coefficient of the Deflection Magnet, -...- Sebo eee ee eee eea teens ees reneeeees xliii 
Coefficient Constant for High and Low Temperatures, ...---.-+-+-sssecessee+e xliii 
Temperature Coefficient of the Bifilar Magnet by hot-water experiments, xliv 
Coefficient Constant for High and Low Temperatures,.-..-- feet eneeeet eee eneseeeteneanes xliv 
b 
