A VISIT TO AN OBSERVATORY. u 



were raised appreciably above that which is found out- 

 side, the heated air from the interior would pour out 

 through the opening, and the disturbance thence arising 

 would produce a mixture of air of different degrees oi 

 density, which would be quite sufficient to impair the 

 delicacy of the telescopic images. Wind, if unattended 

 with clouds, is, as a rule, not injurious to good seeing, 

 though the comfort of observatory work is greatly promoted 

 by a tranquil atmosphere. 



And now as to the objects which the visitor to the obser- 

 vatory should specially ask to see. It must be borne in 

 mind that many of the most interesting objects to the 

 astronomer are almost completely devoid of effectiveness 

 from the merely spectacular point of view. A grand 

 nebula, for instance, will often have portions so faint, that 

 however we may find it necessary to represent them in 

 drawings, they are in the field of the telescope only to be 

 seen by most assiduous attention with an eye especially 

 trained for such work. The visitor will hardly feel con- 

 tented if he be desired to look at something which he 

 may only have a chance of seeing after he has steadily 

 gazed for several minutes at one place. There are, how- 

 ever, some splendid objects in the sky against which no 

 objections of the kind can be alleged, and it is to these 

 that we specially commend the attention of a visitor who 

 is anxious to see some of the wonders of the heavens. 



The celestial objects which I have now specially in view 

 are three : they are the planet Saturn, the star cluster in 

 Perseus, and the great nebula in Orion. Any one who 

 has had the gratification of witnessing these objects 

 on a cloudless sky, and through a telescope of adequate 



