MEMORANDA. 



173 



Prevention of Olarc from ArtlHcial I^lght. — The following Very 



simple plan for correcting the painful glare of artificial light, 

 particularly gas light, in microscopical investigations with 

 low powers may have been adopted by others, but as none of 

 my microscopical friends are aware of it, and as I can find no 

 allusion to it in any works on the microscope with which I 

 am acquainted, a short note on the subject may not be out of 

 place amongst your ' Memoranda.' I have had slips of bluish- 

 grey glass of various shades cut to the size of an ordinary 

 glass slide three inches by one. One of these blue slips I 

 place upon the stage under the glass slide bearing the object, 

 or, if more convenient, place the object to be examined upon 

 the blue glass itself. This little contrivance renders the 

 observer quite independent of a blue chimney-glass to his 

 lamp, and enables him readily to change the tint of the light 

 and adapt it to the particular object he is examining at the 

 moment. By this plan the yellow light of common gas is 

 converted into a pure and white light, approaching very closely 

 to that of daylight. The blue glass may be obtained from 

 any working optician, being the glass used in the manufacture 

 of blue spectacles, and I am confident the observer will derive 

 real comfort from its use in the manner indicated. — Ferguson 

 Branson, M.D., Sheffield. 



inagnetic Stage. — I send you a drawing and description of 

 a magnetic object-holder, not liable to an objection incidental 

 to the otherwise excellent arrangement described by Mr. 



Busk, in the July number of the ' Micro- 

 scopical Journal, inasmuch as it is ap- 

 plicable to the stage of any microscope, 

 whether simple or not, and also requires 

 no new live-boxes or object-holders, being applicable to those 



