378 Miscellaneous Intelligence. 



or of a kmp or candle, as may be eligible, or their reflected light 

 from the speculum. 



The magnifying power of this reflecting microscope is consi- 

 derable, and it is varied and very greatly increased by applying 

 different eye-glasses, as in the astronomical telescope ; and, 

 therefore, to render the instrument also equally useful for lesser 

 magnifying powers, Mr. Cuthbert has contrived to remove the 

 reflecting part from the body of the microscope, and to substitute 

 for it a short tube, into which the usual buttons with object-glasses 

 can be screwed, as in the common compound microscope ; the ad- 

 justing stage, and forceps, and the illuminating speculum being 

 also equally applicable to the microscope in this state ; and to 

 render the microscope an universal one, he has fitted a ring with 

 a screw inside of it to the triangular bar, and the latter to the 

 body of the microscope, and he thus converts it into a single mi- 

 croscope, or megalascope ; the buttons with the object-glasses of 

 the compound microscope screwing into the ring, or lenses of less 

 magnifying powers being substituted in place of them. 



The powers of this instrument, when applied to difficult test- 

 objects, were very evident ; the minute ribs on the feathers of a 

 moth's wings were shewn with the utmost accuracy and detail, as 

 were also the lines upon the coloured scales of the diamond 

 beetle, by which the colours are produced. In the hair of a mouse 

 also, where usual microscopes only shew dark-coloured spots, 

 longitudinal wavy lines or furrows were most distinctly visible. — 

 Tech. Rep. viii. 285. 



6. On the alteration in the bulk of successive portions of Air 

 introduced into a Torricellian Tube. 



To the Editor of the Quarterly Journal of Science. 



Sir, — Wishing to know the effect on the power of a vacuum of 

 introducing into it certain portions of air, and not being able to 

 meet with any information on the subject, either in the books I con- 

 sulted or from several men of science with whom I conversed on 

 the subject, I made the following experiment. As its result was 

 different from what was anticipated, I think it may be useful to 

 others, and trouble you with this communication, with a view to 

 its publication in the Journal so ably conducted by you, if you 

 think it deserving of a place in it. The experiment being made 

 for a practical purpose, no more accuracy was attempted than was 

 necessary for that purpose. The following statements, however, 

 do not deviate much from the truth. 



A tube about thirty-two inches long was filled with mercury, 

 and inverted in it ; the mercury in the tube standing at twenty- 

 nine inches above the surface of that in the basin, I introduced 

 into the former a certain portion of air, having previously ascer- 



