While telescopes were achromatized as early as 1733, most works on the subject date the first efforts to do this for the microscope as later than 1800,culminating in Chevalier's and Tully's objectives about 1923.
But there was an earlier achromatic microscope although of but low power, for in 1771, Benjamin Martin published a pamphlet describing a Microscopium Poly-dynamicum on the title page of which is stated - "Also the Method of Constructing a Microscope of This Kind With One Achromatic Lens Only." Opposite the title page is a plate containing a diagram of this miscroscope showing the lens to consist of a double concave between two double convex units.
In the latter case, Martin explains that this lens is one used as an objective in an achromatic opera glass. Following are pertinent extracts from his rather profuse further explanations:
"Now the very same Achromatic Lens, if applied in the preceeding construction, will become the Object-Lens of an Achromatic and Polydynamic Microscope; and which will magnify in every degree from 8 to 40 or 50 times."
"But a Power of Magnifying 40 times will be found full sufficient to give a most delightful view of all small objects in general as the Aperture here exceeds that of a Common Microscope as much as it does a common-Telescope, being 3 to 6 tenths of an inch."
To get an idea as to the performance of such a lens I fitted a very old opera glass lens, such as Martin described with an aperture of 5/8 inch, so it could be used as an objective and compared it with an old non-achromatic objective. Both were worked at a magnification of 40 diameters, the highest that Martin recommends using a Tolles 1/4 inch solid ocular with the opera glass lens and a 2 inch Huygoniass with the non-achromatic. The former gave good view of Triceratium farsias and proboscis of blowfly, including the servations of the pseudo-trachea, while the latter failed on both tests. In fact, the superiority of the achromatic was so marked that it is difficult to understand why more than thirty years were allowed to pass before further efforts were made in the same direction.