1900] MICROSCOPICAL JOURNAL [177 



have advised many beginners to commence simply by hold- 

 ing the hand a short distance from the eye, and to gradu- 

 ally move it further away as they gained experience, un- 

 til finally it was no longer necessary at all. All workers 

 hare a tendency to use one eye more than another ; and 

 in this case the eye most used becomes generally rather 

 less sensitive to brightness of image, but more capable of 

 perceiving critical points. But exerj worker should learn 

 to use either eye with equal facility. 



Various tints of blue or yellowglasses,oradiscof ground 

 glass, are useful for moderating the light, and in some 

 cases for accentuating the image. 



Remember to use no higher magnification than is abso- 

 lutely necessary. The real microscopist uses the lowest 

 power that will serve his purpose, for reasons that a very 

 slight acquaintance with the microscope makes abundant- 

 ly evident, and in all probability the most generally used 

 lens is that of the modest inch. 



Remember also that the fine adjustment is a delicate 

 piece of mechanism, and then endeavor to save it (and the 

 mechanical stage, if there be one) from the very first. 

 Any one of the microscopes we have described will satis- 

 factorily and easily focus £inch by means of the coarse 

 adjustment alone. Do not bear heavily upon any of the 

 adjustments ; endeavour to balance them gently between 

 the finger and thumb, that the motion may be uniform ; 

 and do not on any account roll the fine adjustment by 

 pressing one finger to one side only of the milled head, 

 or else trouble may follow. -Science Gossip. 



MICROSCOPICAL NOTES. 



Society Screw. — The details of screws for objectives 

 prescribed by the Royal Microscopical Society in 1857 are: 

 Whitworth thread, i. e., a V-shaped thread, sides of thread 

 inclined to an angle of 55 deg. to each other,one-sixth of the 



