TRANSACTIONS OF SECTION A. 577 



The conclusions drawn from tlie whole investigation were as follows : — 



1. There is an alternate increase and decrease in the length of a sunspot period, 

 teckoning from minimum to minimum, 



2. The epoch of maximum varies regularly with respect to the preceding 

 minimum. 



The amplitude of this variation about the mean position is about 



± 0'8 year. 

 The cycle of this variation is about thirty-five years. 



3. The total spotted area included between any two consecutive minima 

 varies regularly. 



The cycle of this variation is about thirty-five years. 



4. There is no indication of the fifty-five-year period as suggested by Dr. Wolf. 



5. The climate variations indicated by Professor Briickner are generally in 

 accordance with the thirty-five-year period. 



6. The frequency of auroras and magnetic storms shows indications of a secular 

 period of thirty-five years. 



Department II. — Meteorology. 

 The following Report and Papers were read : — 



1. Report on Meteorological Observations on Ben Nevis, 

 See Reports, p. 54. 



2. The Seismograjjh as a Sensitive Barometer. 

 By F. Napier Denison, Meteorological Office, VictoHa, B.C. 



Since the installation of a ' Milne ' Seismograph in connection with the Meteoro- 

 logical Office at Victoria, B.C., in September 1898, the author has taken up the 

 study of the various movements of the horizontal pendulum apart from those 

 caused by earthquakes. 



In order to make a thorough investigation of this phenomenon, the author has 

 taken the photographic records from this instrument for the years 1899 and 1900, 

 amounting to over 3,000 feet of paper, and with a millimetre and time scale has 

 measured the amounts and times of occurrence of all changes, including the diurnal 

 and longer period deflections. These observations have been entered in a specially 

 designed register, and as these observations are often of sufficient amplitude to 

 necessitate the resetting of the boom by altering the levelling adjustment, it has 

 been necessary to correct the above readings in order that the true and continuous 

 movement be obtained during these years. 



By studying these corrected observations in conjunction with the Victoria 

 Synoptic "Weather Charts, the author became convinced that most of these move- 

 ments were due to meteorological causes. In order therefore to be able to pursue 

 this study further, he has plotted these observations upon -1 inch squared paper : 

 the time scale used was 2'4 inches per day, and •! inch to equal one millimetre. 

 Above this curve for each month was plotted the Victoria barometer from the tri- 

 daily observations, and surmounting this was entered the tri-daily record of the 

 direction and velocity of the winds and precipitation. 



The results from the plottings for the year 1899 when studied in conjunction 

 with the corresponding weather charts proved so inter(isting that a brief paper 

 upon this subject was read before the last meeting of the Royal Meteorological 

 Society. Since then the author has completed the plottings for 1900, and, in order 

 to increase their value, has added the Victoria tidal curve also. 



