SCIENCE 



A WEEKLY RECORD OF SCIENTIFIC PROGRESS. 



ILLUSTRATED. 



Entered in the Office of the Librarian of Congress, at Washington, D. C. 



No. 64,-Vol. II. 



September 17, 1 881 



Price 1 O 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. 



(Monocular.) 



send FOR CIRCULAR. JOHN W. SIDLE & CO., Lancaster, Pa. 



