APPROACHING SUNSPOT MAXIMUM. 



J. T. LANNEAU. 



The condition of the sun's surface as to spots — when most 

 pronounced, most persistent — is clearly a matter of judg-ment, 

 and therefore must lack precision as to date. 



The last maximum occurred in or near the year 1893. 

 Thereafter, for six or seven years the spots diminished in size 

 and number. During- the past three years it has been a very 

 rare occurrence to see on the sun even a small spot. But be- 

 ginning last July, there is now a decided renewal of solar 

 disturbance. 



My observations at Wake Forest are made with a five inch 

 equatorial. It has a clock work motor, and also two adjust- 

 ing rods at the eye end for movements in declination and right 

 ascension. 



A polarizing eye-piece is so used as to show the sun's disk 

 reversed east and west, but normal north and south. 



In default of a micrometer attachment for exact determina- 

 tion of size and location of spots, approximate measurements 

 are made by stopping the clock work, and then noting inter- 

 vals between transit of spot and transits of sun's east and west 

 limb. Obviously, the distances are proportional to the inter- 

 vals of time. 



Measurements are also made without stopping the clock- 

 work, by using each adjusting rod as a micrometer screw. To 

 so use them, I first find by careful repetition the number of 

 turns or partial turns of the declination rod to move the hori- 

 zontal wire of the eye-piece north and south the full breadth 

 of the sun's disk; and in like manner, the number of turns of 

 the other rod to move the vertical wire east and west across 

 the disk. 



Then, using the rods in turn, relative distances at right 

 angles are found. Points are thus located, and lengths deter- 

 mined. 



