EECREATIYE SCIENCE. 



213 



now TO USE THE TELESCOPE. 



" Telescope Teachings :" A Familiar Slcetcli 

 of Astronomical Discovery. By the Hon. 

 Mrs. Ward. 



A RTJDiMENTAEY book on th.e practical study 

 of astronomy, and as such, it would be impos- 

 sible to find one more attractive to the novice. 

 Indeed, the work is well calculated to make as- 

 tronomers of those who have not studied the 

 subject. Mrs. Ward shows, in a clear man- 

 ner, how very much can be done at a small 

 cost, both in labour and money. Many of 

 the plates (of which the work is profusely 

 illxistrated) are admirable pictures, faithfully 

 executed. Donati's Comet and the Eclipse 

 of 1858 may more especially be noted; in 

 fact, those who desire (and who does not ?) to 

 have the splendid comet of that year brought 

 truthfully before them, should by aU means 

 possess this book. G-reat credit is due to the 

 authoress, to the artist, and to the publisher ; 

 each have done their part well, so that the 

 work must have, as it really deserves, a great 

 circulation. 



We extract, as an example of the author's 

 method, the following directions for the ob- 

 servation of the spots on the sun by means 

 of the telescope : — 



" We must place a piece of dark-coloured 

 glass before the eye-piece of the telescope, as 

 the sun is far too bright to be looked at 

 without this protection. There are two other 

 little precautions which we would recommend 

 to the observer : firstly, to point the teles- 

 cope by observing its shadow on a piece of 

 paper, held to receive it ; when this shadow 

 is perfectly round, it will be found that the 

 instrument is exactly pointing to the sun ; 

 secondly, prepare a flat piece of pasteboard, 

 with a hole cut through it of the diameter of 

 the telescope, and when the instrument is 



properly adjusted, slip on the pasteboard to 

 screen the unemployed eye and the head and 

 face from the heat of the sun. The first 

 precaution is recommended to save the ob- 

 server from being dazzled in vain endeavours 

 to ' hit the sun' in the ordinary way, and 

 both are more easily and quickly done iu 

 practice than in description. 



"Looking now through the telescope, 

 should the dark glass used be of a reddish 

 shade, we shall see a round orange-coloured 

 disc in a black sky. On this disc there are 

 generally a few black spots, somewhat re- 

 sembling small blots or splashes of ink. When 

 examined with care the larger spots prove to 

 be not uniformly black, and not circular in 

 shape, but of two dark shades, and of irre- 

 gular outline. 



" It is sometimes practicable to look at 

 the sun through a fog or thin cloud without 

 using the coloured glass. Its disc then 

 appears white, and the spots are of two shades 

 of brown. 



" The opinion generally held by astrono- 

 mers concerning these spots is, that they are 

 the comparatively darh solid hodyoftJie sun, 

 laid bare to our view by immense fluctua- 

 tions in its luminous atmosphere ; that the 

 sun has at least two atmospheres, upper and 

 lower, and that the darker ^^sxt of the spots is 

 where the sun is seen through a rent in hoth 

 layers of atmosphere ; the lighter, where 

 one layer still covers it. Hecent observations 

 have indicated that there are three grada- 

 tions of shade, in some spots at least, the 

 centre being the darkest. 



" The solar spots are not permanent. 

 When watched from day to day, they are 

 observed to enlarge or contract, to change 

 their forms, and at length to disappear alto- 

 gether; and new ones appear where pre- 



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