108 



To Take Care of a Stand. One of the first 

 rules should be to keep the instrument free f ram dust. 

 This may be done in a manner formerly prescribed. 

 If dust settles on any part of the instrument, remove 

 it first with a camel's hair brush, and then wipe care- 

 fully with a chamois skin, with the grain of the finish 

 and not across it, as in the latter case it is likely to 

 cause scratches. Keep the working and sliding parts 

 absolutely free from dust, as this grinds and will 

 thus soon cause play. 



Use no alcohol on any part of the instrument, as it 

 will remove the lacquer. As the latter is for the pur- 

 pose of preventing oxydation of the metals, it is 

 important to observe this rule. 



In using the draw-tube impart a spiral motion. In 

 instruments which have no cloth lining, a straight up 

 and down movement should be employed, as the tube 

 will otherwise become scratched. 



If it becomes necessary to lubricate any of the 

 parts, use a slight quantity of soft tallow or good 

 clock oil. 



In an instrument which is in constant use, it some- 

 time occurs that the pinion works loose and occasion- 

 ally to such an extent that the body drops of its own 

 weight. Tightening screws are provided to take up 

 the play in the Professional, American Concentric, 

 Universal, Physician, Biological and Library Micro- 

 scopes these are in the back of the pinion. In the 

 Investigator, Model and Family Microscopes, they 

 are seen in the slide by removing the body. 



