118 THE CANADIAN NATURALIST. [March 



several nights during each month. Several slight shocks of earth- 

 quakes were felt both at Montreal and in its immediate vicinity. 

 The grand meteoric display was well seen from llh. 35m. P.M. 

 on the 13th November, to 3h. 45m., A.M., of the 14th, and was 

 most profuse and brilliant. 



MISCELLANEOUS. 



Illumination of Microscopic Objects. — Notwithstanding 

 the many ingenious methods of microscopists for the illumination 

 of the minute objects they study, none of them seem hitherto to 

 have been based on thoroughly artistic, if, indeed, even on 

 sufficiently correct principles. The new hemispherical condenser, 

 invented by the Rev. J. B. Reade, is certainly, in one point of 

 view, the most correct in principle, and practically the best as 

 far as the proper delineation of objects is concerned. Of its value 

 in bringing out fine lines and markings on the scales of Podura 

 angulatum and various other test objects a single inspection would 

 be sufficient for the most obdurate disbeliever in its efficacy. 

 The principle is a modification of semi-circular illumination, — or 

 illumination from one side only, as artists adopt in their pictures. 

 An ordinary achromatic condenser throws the light all round the 

 object, and, consequently, as each half of the circle of illumina- 

 tion throws shadows from any prominences or thicknesses of the 

 object in opposite directions, so there are also illuminations of 

 the shadows from both sides of the circle of light, and the defini- 

 tion of the object, which is only brought out by the depth of the 

 shadows, must be weakened. Mr. Reade invented his condenser, 

 as many other things have been invented, by an accident. He 

 placed a lamp directly in front of his object, and another lamp at 

 right angles to it at the side. The shadows were consequently 

 artistically thrown upon the object, and he found the definition 

 of it wonderfully increased. From this it occurred to him that 

 by using a hemisphere of glass and covering the top or flat sur- 

 face with two oversliding diaphragms, pierced with certain orifi- 

 ces, he could throw one ray of light longitudinally and another at 

 right angles horizontally over his object ; and that by means of 

 the overcrossing of the intermediate slits of the diaphragms he 



