No. :.I ITL'. 



Comparators, Reading Telescopes, Screw Micrometers. 



225 



51469. 



51470. 1 : 7. 





51 472 A. 1:5. 



51 472 B. 1:5. 



51471. 1 : 4. 



51.467. Comparator ior rules divided with lines 



Lengths up to 1 m can be compared with this instrument. It consists of an iron bench, and two 

 reading microscopes can be moved along the entire length of this bench, being also capable of lateral 

 motion. The microscopes have micrometer eyepieces with movable line. If desired, Fraunhofer micro- 

 meters are supplied at a proportionate increase in price. 



51.468. Apparatus for Calibrating and Testing Thermometers (Comparator), Figure. . . 



Two micrometrically adjustable reading microscopes can be moved along the length of a hori- 

 zontal rail. 



51.469. Reading Telescope, on stand, Figure, rack and pinion focussing; objective 25 mm 

 aperture and 200 mm focal length, with two magnifications Xl2 and x24, astronomical; 

 quite free from iron parts so as to enable galvanometrical and magnetometrical read- 

 ings to be made with it 



51.470. Simple Reading Telescope, Figure, with objective 24 mm in diameter and cross 

 lines, with horizontal and vertical rotation, and vertical adjustment 



51.471. Screw Micrometer (Fraunhofer's), Figure, measuring accurately 30 mm to Vsoo mm ; 

 with low power microscope capable of rotation about a horizontal axis and sliding on a 

 pillar, so that measurements can be made in any direction 



51.472. Screw Micrometer (Fraunhofer's), Figs. A and B, on a folding stand, for vertical 

 and horizontal observations; can also be used as a microscope with detachable and 

 sliding microscope table. Price, in box 



s. d. 

 47.10.0 



17.10.0 



5.10.0 



1.15.0 



14. 0.0 



37.10.0 



Reading Telescopes for Mirror-Reading see section: "Electricity". 



d. iL'i;. .v,;iL'. 

 42!), 4:ili, 4L-X. 



15 



