A COMPARISON OF THE BOSTON OPTICAL WORKS 'A' MODEL AND THE BULLOCH 'CONGRESS' MODEL

1880's

In comparing the Dalton-BOW microscope to other large stands of the time, it would seem reasonable to compare it to Bulloch's largest stand, the Congress model for two reasons. First Bulloch's influence in the construction of the BOW stand is readily apparent, and secondly they are both the largest stand of their respective makers. In comparing them, they are both very large. The Congress sits on taller pillars; height from the table to the center of inclination of the Bulloch is 7 1/2 inches while on the Dalton it is 6 1/2. The spread of the flat tripod is actually wider for the Dalton being about 11 3/8 inches while the Bulloch is about 10 1/4. The outer diameter of the stage ring for the Dalton is 5 inches while for the Bulloch it is 5 1/2, but note that the rotating part of the Dalton stage is of smaller diameter than the ring(4 1/2 inches), while for the Bulloch the rotating portion is the same size as the ring or slightly larger, overlapping the top of the ring. Note that both have stages that are quite thin, to allow extreme oblique illumination. When one compares the feet, the mechanical stages, and the dual swinging substages, Bulloch's influence seems clear. This is not surprising, since Bulloch worked for the BOW from 1871 to 1872, when Tolles was still superintendent. Dalton was the principal brass worker when Bulloch joined the company, and undoubtedly his work and ideas continued to be well known to Tolles and Dalton after Bulloch returned to Chicago.