SCIENCE 



A WEEKLY RECORD OF SCIENTIFIC PROGRESS. 



ILLUSTRATED. 



Entered in tin Office of the Librarian of Congress, at Washington, T>. C 



No. 72-Vol. II. 



November 12, 1 881 



Price lO Cents. 



"Acme" No. 2. 



Monocular, . $ioo 



Binocular, . . . 145 



"Acme/' No. 3. 



Monocular, . . . $50 

 Binocular, 75 



" Acme" No. 4. 



The favorite Laboratory 

 Stand, . . . $25 



With 1 inch and % inch 

 objectives, . . .50 



Special Terms made with 

 Colleges. 



"Acme" Lithological. 



A new Stand, after the pat- 

 tern of the No. 3, for the study 

 of Rocks ; convertible in an 

 instant into an ordinary mon- 

 ocular. $92 



All our Stands 



have same size of tubing and 

 sub-stage fitting, so that eye- 

 pieces and accessories that fit 

 one Stand can be used with 

 all. 



"Congress" Turn-Table 

 Patented, $6.50. 



Gem Turn-Table, $2.50 



Do. Do. with improved 

 centering adjustment, $3.25 



LITHOLOGICAL MICROSCOPE. 



SEND I OR CIRCULAR. 



(MONOCULAR.) 



JOHN W. SIDLE & CO., Lancaster, Pa. 



