SCIENCE 



A WEEKLY RECORD OF SCIENTIFIC PROGRESS. 



ILLUSTRATED. 



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



No. 47-VoI. II. 



May 21 , 1 881 



Price lO Cents. 



The "Acme" Microscopes. 



"Acme" No. 2. 



Monocular, . . $ioo 

 Binocular, . . . 141 



"Acme," No. 3. 



Monocular, ... $45 

 Binocular, ... 70 



" Acme" No. 4. 



The favorite Laboratory 

 Stand, ... $25 



With 1 inch and inch 

 objectives, . . -45 



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. 



All our Stands 



have same size of tubing ma 

 sub-stage fitting, so that eye. 

 pieces and accessories that fit 

 one Stand can be used with 

 all. 



"ACME" No. 4. 



"Congress" Turn-Table 



Patented, $6.50. 



Gem Turn-Table, $2.50. 



Do. Do. with improved 

 centering adjustment, $3.25 



<£>$g>~ 



HOLMAN'S COMPRESSOR, THE LATEST AND THE BEST, $4. MECHANICAL FINGER, $5. 

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



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