292 Solar Observation. 



Now to employ this combination. Let the star be found as 

 before, and the velocities in azimuth and altitude relatively 

 adjusted; the cord from the moderator mover is now taken 

 between the finger and thumb and passed round a small pin 

 on the afterpart of the board or base of the stand, or it may 

 pass under a little plate of brass and be nipped by a screw. 



The lamp now takes charge of the whole affair, and slowly 

 and steadily moves the stand towards the left, thus following 

 the horizontal motion of the star or planet ; but as the other 

 fixed cord is passed round the sheave e, this movement canuot 

 take place without turning it, and thus the vertical motion is 

 obtained at the same time. The flow of oil is regulated by the 

 stopcock ; and if a greater force is required than that of the 

 spring in the cylinder of the lamp, a weight of any amount can 

 be placed on the top of the rack. 



N.B. When the star to be observed is on or near the 

 meridian no movement in altitude is required, so the little 

 wedge is pushed in, and the disc revolving free from the cone, 

 the winch may be transferred to the square above of the upper 

 spindle. 



SOLAR OBSERVATION.— TRANSITS OF JUPITER'S 

 SATELLITES. 



BY THE EEV. T. W. WEBB, M.A., F.K.A.S. 



The most magnificent object of all human contemplation is, 

 beyond a doubt, the great star to whose influence our planetary 

 system has been subordinated by its Creator. Other suns, 

 there is reason to believe, may be superior to it in magnitude, 

 or at least intrinsic splendour, but in a remoteness which even 

 the velocity of light, that reaches us in about eight minutes 

 from the sun, can only mcasuro by intervals of whole years, 

 their individual features arc, and ever must remain, unknown 

 to us. As it was recently remarked in a very interesi ing paper. 

 with which our readers are familiar, " We never see the Stars/' 

 On the oilier hand, the distance of our own sun is such as to 

 place liim within reach <>f even our smaller instruments, and to 

 bring that amannous lined of light clearly before the spectator's 

 eyo;* while the tnagnil ude, the variety, and the strangeness of 



* A power of ISO represent* tho solar disc under so great an angle that its 

 entire breadth, if il were comprised in one field, would fill up the whole 

 sky from the horizon to the zenith. This may appear at first sight almost 

 incredible, but it is matter of easy proof. Tho sun's diameter averaging a little 

 moro than half a degree, LBO tune, or one sun magnified that number of limes, 

 would occupy a space of upwards of !)0°. This may serve to show how fallacious 

 may be tho judgment of our sight in the absence of any known object of com- 

 parison. 



