Care of the Coarse Adjustment. Special 

 care should be given to keep the coarse adjustment 

 free from dust as its effect is particularly pernicious. 

 The slides and rack and pinion are necessarily exposed 

 and the lubricant is apt to catch dust and also to gum. 

 The tube should be occasionally withdrawn from the 

 arm and the slides carefully wiped with a cloth 

 moistened with benzole. Lubricate by applying a 

 small quantity of soft tallow or paraffine oil to a cloth 

 and wiping well over the surfaces, removing the super- 

 fluous amount with a dry cloth. The teeth of neither 

 rack nor pinion should ever be lubricated. An 

 occasional cleaning of the teeth with an old tooth 

 brush is advisable. 



It is advisable occasionally to lubricate the pinion 

 shank on both, sides of the arm with a very minute 

 quantity of paraffine oil. 



If the pinion works loose from jar incident to trans- 

 portation or long use, which sometimes occurs to such 

 an extent that the body will not remain in position, 

 increase the friction upon it by tightening the screws 

 on the pinion cover. 



Fine Adjustment. In a general way it may be 

 said that if the fine adjustment ceases to work satis- 

 factorily the instrument had better be returned to the 

 maker, as it involves the most delicate working and 

 few people are conversant with its construction. There 



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