252 



KECEEATIVE SCIENCE. 



plained on the supposition of the existence of another 

 and interior perturbing planet. The suspected planet 

 has heen found ; it was discovered transiting the sun's 

 disc on March 26, 1859, by M. Lescarbault, at Orgeres, 

 in the department of Eure-et-Loire, France. Sus- 

 picious-looking objects were seen on the sun's disc on 

 January 6, 1818, by Mr. Lloft, and in the summer of 

 1847, by Mr. B. Scott, the Chamberlain of the City of 

 London, but neither of these observations can refer to 

 the new planet, though it is by no means improbable 

 that it is identical with the object seen by Cassini in 

 1672 and 1686, by Short in 1740, and by Montague in 

 1761, and by them considered to he a satellite of Venus. 

 M. Le Verrier has computed an approximate set of 

 elements, from which it appears that another passage 

 over the sun's disc will take place sometime during 

 the fifteen days included between March 25 and April 

 10, and September 28 and October 13, 1860, and also 

 that the period of the planet's revolution round the 

 sun is about twenty days. Further information is 

 anxiously looked for. 



Stereoscopic Phenomena. — A Youthful Stereoseopist 

 offers Mr. Noteworthy the following remarks :■ — " I have 

 seen some lenses in the shape of the annexed diagram : 

 a a, lenses of the stereoscope ; bb, raj's from lenses on 

 the photograph. I think, from the shape of the lenses, 



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that their rays would cross each other before con.ing 

 in contact with the picture. Therefore, if a small 

 photograph were placed in the stereoscope, the right- 

 hand lens would cast its ray on the left side of the 

 picture, and the left lens on the right side, and the 

 right side of the photograph would appear to be seen 

 by the left eye, and the left by the right eye." — Another 

 friend explains to Mr. Noteworthy, that " if a person 

 looks long and steadily at a small photographic 

 portrait through a stereoscope, so as to see one-half 

 only with each ej-e, the two halves will unite cor- 

 rectly, except that the half segu hy the left eye is 



(tome, at least) a little higher than the other. This 

 united picture, which is not clear, especially on 

 one side, requires to attain it a fatiguing effort (like 

 that which many persons experience on first looldng 

 through a stereoscope before they attain the stereo- 

 scopic effect), but afterwards is at once perceived. The 

 apparent interchange which Stekeo saw is perceived 

 only at first." 



A Cheap Telescope. — A really useful telescope 

 may be made by obtaining a single convex lens of four, 



o five, or six feet focus, which lens can be had 

 of an optician for half-a-crown. The tube 

 may be made of paper, of the required length, 

 to suit the focus of the object-glass. Make 

 also two more tubes of tin for an eye-piece, 

 one to slide within the other, the larger one 

 to slide in the tube of the telescope. The 

 annexed diagram will explain what we mean : 

 D is the body ; a is the object-glass ; b c is the 

 ej'epiece. This is somewhat the same tele- 

 scope as described in a fonner paper, but with 

 this material difference, a compound eye-piece 

 is used in this one, whilst in the former only 

 a single eye-glass is used, b is a concave lens, 

 and c is plano-convex. By placing b before c, 

 it doubles the power of the eye-piece, and gets 

 rid almost entirely of the prismatic colours, 

 whilst its definition approaches that of an 

 achromatic. This eye-piece can be used as a 

 pancratic. If you pull c out, you must push 

 B nearer to the object-glass. But two or three 

 trials will be the best teacher of what we in- 

 tend to prove. This telescope will show the 

 satellites of Jupiter, and also the dark belt 

 across the body of the planet*, (b, 4 inches, c, 

 4 inches.) 



English Copper Coinage. — A correspon- 

 dent asks Mr. Noteworthy about the value of 

 ■^ some coins, to which he has thought it best to 

 reply in a note which may interest all readers. The first 

 copper coinage issued in bulk by British sovereigns was 

 thatof Charles II., in 1665. It consisted of halfpence and 

 farthings. The farthings had on the reverse the figure 

 of Britannia, with the motto, " Quatuor Maria vindico." 

 On the obverse they had the head of the king, with 

 " Carolus a Carolo." On the edge, done by a newly- 

 invented milling machine, was the motto, " Nummorum 

 famulus," meaning (it is conjectured) the servant of 

 7noncy, as being the lowest kind of English money. A 

 farthing of this issue, if as perfect as whgu first struck, 

 that is, " a flew de coin" as they say, may he worth a few 

 shillings ; if at all rubbed, it is only wortli a few pence ; 

 and if much rubbed, it is only worth its weight in 

 copper ; those of the same pattern, issued in 1672 

 (the same devices, except in the motto of Britannia on 

 the reverse), are much more common, and, therefore, 

 worth less. The threepenny, foui-penny, and sixpenny 

 silver pieces of Queen Elizabeth are almost all com- 

 mon, and worth but a trifle more than their intrinsic 

 value in silver. There are a few rarities in the series, 

 but not likely to be picked up in a chance way. 



