-'/ 



CA.. 



W.5. 







•fef'f' 



r 



V 



WRCCTOR 



Figure 12. — Cambridge, Massachusetts, showing the location of the Alvan 

 Clark & Sons establishment along the Charles River (circle at lower 

 right). Prospect Street (circle at center right), where the Clarks lived 

 from 1836 to i860, is also indicated. Courtesy Library of Congress. 



several pieces of scientific apparatus and made them available to scholars 

 for research purposes. One of these instruments was a Clark-made 

 micrometer-level which incorporated a telescope of 4 centimeters aper- 

 ture, supported in Y's and moved by a vertical micrometer screw." 



8 "List of Apparatus Relating to Heat, Light, Electricity, Magnetism, and Sound, 

 Available for Scientific Researches Involving Accurate Measurements," Annual 

 Report . . . Smithsonian Institution . . . 1878, p. 430. 



41 



