434 Sun Viewing and Drawing. 



If now you draw apart the two semi-circular orifices above 

 alluded to, you may readily direct your telescope upon the 

 sun (without dazzliug your eyes, as in the ordinary method 

 whilst so doing), by so adjusting the tube, that the dark 

 shadow cast by it upon the screen shall be a perfect circle. 

 Then, having closely drawn the India-rubber round the tele- 

 scope, and duly attended to the focussing, a perfectly defined 

 and most pleasing image of the magnified solar-disc will exhibit 

 itself, on a scale more or less enlarged, according to the power 

 of the eye-piece employed, or the distance the screen is placed 

 from the telescope. As a general rule, about one yard may 

 be recommended as a convenient distance for producing an 

 excellent effect with almost any eye-piece that the state of the 

 atmosphere will admit of. 



It will be found that, by shifting the tube slightly with the 

 hand, the whole solar disc may be very rapidly and effectually 

 scrutinized, with no more strain to the eyes than if it were 

 being presented to you on a chart ; and with a power of — say 

 about sixty or eighty linear — the most minute solar spot, 

 properly so called, that is capable of formation (for the writer 

 believes they are never less than three seconds in length or 

 breadth), will be more readily detected than by any other 

 method ; as also will any faculae, mottling, or, in short, any 

 other phenomena that may then be existing on the disc* 



The darker your chamber (your camera obscura, in fact) is, 

 the more vivid and satisfactory are the results; and the writer 

 will not easily forget the feelings with which he in this manner 

 watched the progress of the solar eclipse of July 18th, 1860, 

 along with his friends. 



Drifting clouds frequently sweep by, to vary the scene, and 

 occasionally an aerial hail or snow-storm, as mentioned by 

 Mr. Browning in the number of the Register just alluded to ; 

 and the writer has more than once seen a distant flight of 

 rooks pass slowly across the disc with wonderful distinctness, 

 when the sun has been of a low altitude, and likewise, much 

 more frequently, the rapid dash of starlings, which, very much 

 closer at hand, frequent his church tower. 



A transit of any of the inferior planets is also beautifully 

 apparent by this method, as was witnessed by the Honourable 

 Mrs. Ward, on November 12th, 1861, and agreeably- recorded 

 by that talented lady in an illustrated article in the very first 

 number of the Intellectual Observer. 



* An instance of the facility of this method for detecting a very small spot is 

 afforded by the fact, that, in the various accounts of the late eclipse of March 

 6th, 1867 (recorded in the Astronomical Register for the month following), 

 almost all concur in stating that, no spot was observed on the sun, whereas there 

 most certainly was one spot visible about eight seconds in length. , 



