William Boal Rezner, 1824 - 1883

Figure 4. A Rezner-type mechanical finger, mounted onto a microscope's objective lens. The bristle tip is centered over the field of view. After locating a diatom or other item of interest on a slide of specimens, the lens is racked down so that the tip touches the diatom, which usually adhere to each other. Racking the lens up will lift the diatom. A new slide can be placed onto the stage, the lens racked down, and the diatom transferred to adhesive on the new slide. Image from a 1904 article on the topic by A. Verinder.

Figure 5. Excerpt from Eimer and Amend’s 1907 “Catalogue of Bacteriological Apparatus”.

William Boal Rezner was born on July 18, 1824, in Miffinsburgh, Pennsylvania, son of John and Mary Rezner. “Boal” was the mother’s maiden name.

Around 1842, when 18 years old, Rezner moved to Mesopotamia, Ohio, in the northern part of the state, not far from Cleveland. He attended Cincinnati Medical College, graduating in 1846. He then opened a practice in Mesopotamia. Also in 1846, William Rezner married Adaline Tracy. The pair had three girls and one boy.

In 1854, the Rezner family moved to Cleveland.

The U.S. Civil War began in April, 1861. In October of that year, William enlisted as surgeon for the 6th Ohio Volunteer Cavalry, and became Chief Surgeon of his brigade. He reportedly saw service around Gettysburg and Richmond. He served until the war ended in 1865.

A friend and microscope colleague, Charles Vorce, wrote about Rezner, “On his return from the army Dr. Rezner resumed the practice of his profession, and with his naturally great skill enhanced by the valuable experience he had gained during his service in the army rapidly recovered the practice he had surrendered, and speedily advanced until he stood in the foremost rank of the most skillful physicians and surgeons of the day, and had he been gifted with more worldly ambition and less retiring modesty he might have won a renown that would have made his name famous, but he had a horror of anything that seemed to him like boastfulness which led him rather to conceal merits, and undoubtedly operated somewhat to prevent in many cases his receiving the credit which was his due. But to those who experienced his skill he seemed infallible, and no physician or surgeon ever enjoyed a more implicit confidence on the part of his patients than did he.”

In contrast, William Corlett, Professor at Western Reserve University and Fellow of the Royal Society of Medicine, wrote, “Dr. Rezner was an army surgeon, a veteran of the Civil War, but who for many years was more interested in the microscope and of studying diatoms than in following the progress of the surgical art.”

Vorce wrote further about Rezner, “His interest in Microscopy was very great and had extended a period of about twenty years, during which so far as he had time he prosecuted unceasingly the study of various problems connected with it, giving great attention to methods of staining and dissection as applied to pathology. Although a great deal of his work was worthy of publication he could not be induced to publish it, and only his friends and associates learned of it from him, though in turn frequently communicated it to others. He was President the Cleveland Microscopical Society at the time of his decease, and stood at the head of microscopists in the city. His mounting of slides was not excelled by any of the specialists in that line ...”

“His best known invention relating to the resolution of tests was the plating of micrometer lines with silver, by which method the difficulty of resolution was so much decreased that one of the best known microscopists described the result as ‘altogether too easy to be interesting’. By this method Dr. Rezner succeeded in resolving the famous band of 120,000 lines to the inch, which resolution he was the first to accomplish, and which he exhibited at the Buffalo meeting of the American Society of Microscopists, and this method has since had extensive application. Dr. Rezner devised and constructed a special traversing apparatus for use in the resolution of lined tests, and among other devices an improved fitting with universal movements for the Wenham reflex illuminator. He personally constructed several different forms of the Wenham reflex illuminator, numerous solid oculars, immersion illuminators, and various prisms and special fittings of many kinds, for use in special investigations in which he was from time to time engaged… Various other forms of microscopical apparatus in common use were modified and improved upon by him ...”

“Sometime previous to his demise, he had completed a spectroscope of his own manufacture, which was so delicate and so fine an instrument that with it the sodium line, D, in the solar spectrum could be resolved and the nickel line seen.”

His interest in microscopy and diatoms led to the invention of his famed mechanical finger (Figures 3 and 4). As with his other inventions, Rezner did not broadcast a description of this apparatus. Vorce wrote of it in 1879, along with a description of his own methods for arranging diatoms into patterns. Examples of Vorce’s work can be seen in the essay of his life and works, elsewhere on this site.

Rezner’s mechanical skills extended to larger scales. He apparently designed part of a bridge in Cleveland.

In the summer of 1883, he “attended his patients as usual up to Sunday, July 15th, when he experienced an attack of angina pectoris, from which, however, he recovered somewhat and during the week even visited one or two of his patients, and on Saturday, July 21st, he had arranged to visit a patient in the afternoon, feeling then much better than he had during the week. He ate dinner on that day as usual, enjoying well, and after dinner lay down for a short rest and evidently must have experienced a sense of oppression as he tried to arise, and falling forward on his face, expired without a struggle."

Figure 6. “Section of knee joint of foetus at 5 months”, prepared ca. 1870s by W.B. Rezner. Photographed with a 3.5x objective lens and C-mounted digital SLR camera on a Leitz Ortholux II microscope.

Resources

Bausch & Lomb (1896) Microscopes, Microtomes, Apparatus for Photo-Micrography, and Bacteriology Laboratory Supplies, Dr. Rezner's mechanical finger listed on page 196

Corlett, William (1920) Early Reminiscences, Lakeside Press, Cleveland, pages 41-42

Davis, George E. (1882) Practical Microscopy, second edition, D. Gogue, London. description of Rezner’s mechanical finger, pages 293-294