DESCRIPTIVE CATALOGUE. 



Fig. 684. 



178 BENJ. PIKE'S, JR 



Military Telescope. (Fig. 

 683.) This cut represents a 

 military telescope, the tubes 

 closed, having a sun-shade 

 tube, the extra cost of which 

 is from 50 cts. to $1.50, ac- 

 cording to size. 



Achromatic Ship Telescope. 

 (Fig. 684.) The achroma- 

 tic ship telescope, represented 

 in the cut, is employed very 

 extensively both on the land 

 as well as at sea, in view- 

 ing distant objects. The full 

 length of this telescope, when 

 drawn out, is 3 feet, and when 

 closed 21 inches if with a 

 single draw ; 15 inches if with 

 two; or 12 inches if with 

 three. Those with one draw 

 are preferred, having larger 

 glasses in the eye-piece. The 

 case is two and a half inches, 

 and is usually of mahogany covered with 

 bridle leather in the best instruments, and 

 having a sun shade at the end for the ob- 

 ject glass, which is also used at sea to pro- 

 tect the glass from the spray. This instru- 

 ment is sometimes called a day and night 

 telescope, from its being suited to use at 

 night as well as in the day ; this is of most 

 use at sea, where it is at times important 

 to see at night an object only partly dis- 

 cerned by the naked eye. To use the te- 

 lescope as a night glass the joint furthest 

 from the eye hole is unscrewed, and the 

 tube containing two lenses taken out ; the 

 telescope will now represent objects in an 

 inverted position, but they will appear more 

 distinct than with the naked eye. 



Price, common make, - - $ 7.00. 

 " best glasses, $9. 00 and $10.00. 

 " leather body, $1 1 .00 and $12.50. 



