222 Miscellaneous Intelligence. 



very shallow curve, and proportional thinness. If a dia^am is 

 made of the curves of any two lenses of the sa7ne penetrating and 

 amplifying' power, formed of glass and adamant separately, it will 

 at once show what their spherical aberration amounts to ; being 

 enunciated in terms of their thickness, as stated above, and which 

 of course is the same, whether they have their curved surfaces 

 exposed to parallel rays, or their flat sides to divergent ones, from 

 a radiant point in their focus, when used as magnifiers. If we se- 

 lect a hemisphere of glass, having its aperture equivalent to its focus, 

 which is absolutely necessary for exhibiting certain test objects, 

 and calculate the longitudinal aberration of a diamond of the same 

 power and calibre, it will be found less than one-sixth of that of the 

 glass ! Again, the chromatic aberration of the adamant is very 

 little more than that of a drop of Water of the same radius, which 

 is scarcely felt at all, when the stone is used only as a single mi- 

 croscope ; so that we thus obtain a kind of natural aplanatic lenji, 

 capable of being carried to an enormous power, which is, in fact, 

 the very beau ideal of the single microscope, necessarily the most 

 perfect instrument of all, when divested of aberration. Of all the 

 improvements in microscopes which have been originated by Dr. 

 Goring, this is perhaps the most important, and the most likely to 

 extend discoveries in minute nature. 



As many individuals have chosen to doubt of the possibility of 

 working diamonds into spherical curves, Mr. Pritchard will be proud 

 to exhibit his instrument to amateurs of microscopic science. 



3. Results of Observations on Falling Stars, made by Professor 

 Brandes, of Breslau. — i. Falling stars move in all directions, rela- 

 tive to a vertical line ; but the number which approach the earth 

 is greater than that of those which move from it. From this it 

 would appear to result that, during the short time for which they 

 are visible, they are subject to the attractive power of the earth. 



ii. Let the real direction according to which these bodies move be 

 ascertained, being referred each time to that of the motion of the 

 earth at the time of observation ; then let a mean be taken of these 

 partial results. If the results are sufficiently numerous, the direc- 

 tion which they will indicate will be diametrically opposed to that 

 of the motion of the earth. 



Falling stars undoubtedly have a real velocity ; but it appears to 

 result, from the preceding observations, that the greater part of 

 their apparent velocity is a mere illusion, dependant upon the mo- 

 tion of the earth. May it not be worthy of remark, that we arrive 

 at a new proof of the movement of our globe, by observing these 

 fugitive and inconstant phenomena ? 



I have no occasion here to call to mind that the true line of 

 motion of the meteor in azimuth and in height, requires the compari- 

 son of simultaneous observations made at distant places. j^iin, 



de Chimie, xxxiii. 413. 



