Biographical Sketch of Joseph ZENTMAYER; Philadelphia Co., PA

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"Philadelphia, A History of the City and its People; A Record of 225 Years"
Publisher: S. H. Clark; Philadelphia; 1912. Vol. 3, page 373
Author, Ellis Paxson Oberholtzer

JOSEPH ZENTMAYER

In the field of science as an investigator, inventor and manufacturer, Joseph Zentmayer led the way -- the pioneer in paths hitherto untrod but which have since become the thoroughfare of many followers. To him principles and truths as old as creation were made plain as he carried forward his investigation and experimentations, acquainting himself with all that the world can furnish in knowledge of that character and then pressing beyond the limits that others had reached to unfold and develop truths new in scientific circles. A native of Manheim, Baden, Joseph Zentmayer was born March 27, 1826. His early education was acquired in the gymnasium of that city after which he entered upon an apprenticeship to an optician of Baden where he obtained "the foundation of the knowledge and skill which has marked him as a correct analyzer and a wonderfully ingenious contriver of mathematical and optical instrumentation." He was afterward associated with some of the principal optical establishments in Karlsruhe, Frankfort, Munich and Hamburg, where thorough training further qualified him for the attainment of the eminent position which he later occupied in the scientific world. In Hamburg he was associated with Repsold Brothers, where his training was of a character that counted as a valuable asset in his later construction of astronomical apparatus.

In young manhood, fired with the spirit of liberty and seeking his country's independence, he took part in the revolution of 1848. The military operations of the revolution, however terminated unsuccessfully and therefore at the age of twenty-two years Mr. Zentmayer sought a home in America. During the succeeding five years he was employed in the best optical establishments in Baltimore, Washington and Philadelphia, his marked ability winning him positions of responsibility. But a laudable ambition and desire for something better and broader that characterized his entire life led him to start out independently in 1853 although practically without capital. With comprehensive knowledge of the scientific principles upon which practical mathematical instruments are manufactured he turned his attention to that business in Philadelphia in a little room at the corner of Eighth and Chestnut streets, equipped with scarcely more than a single foot-lathe. One of his earliest orders came from Dr. Paul B. Goddard for the construction of a large compound microscope. The excellence of the instrument formed one of the foundation stones upon which was builded his local reputation. He became known among scientific men as an expert in his field and the leading histologists, microscopists and mineralogists gave him their patronage. One of his biographers said: "These business connection soon brought with them the pleasant and ever-extending social and scientific associations so common and so universal among those whose life aims are for intellectual good and philosophical research. Although reticent to a degree and unassuming among large bodies of men, yet his uncompromising honesty of opinion when sought for, his constant willingness to help solve the most difficult problems in theoretical and applied optics, and the clear, forcible and logical manner with which he grasped and handled any subject in question, made men seekers of him rather than he of them. Ever thus he was surrounded by distinguished men of all professions and occupations who were interested in microscopical and optical science; men who, as friends and brothers, sought his workshop to take his counsel in the solution of vexed problems in the laws of light; men, who as students came to him to gain his advice as to the best form of construction of instruments of precision; and aye, even overwise tyros willingly found in this patient and unassuming man the calm and dignified correction that they had not supposed themselves able to receive. Most approachable, always cordial, unbiased in his feelings toward the erudities of individual belief and unlimited in his liberality in regard to personal and national opinion, he embraced those qualities that make a man lovable, craved for and sought after."

In his business career, Mr. Zentmayer made continuous advancement. Skill, experimentation and broad scientific knowledge enabled him to reach a high degree of proficiency in the construction of some of the most important mechanical details of the microscope whereby necessary apparatus was simplified and perfected, leading to the attainment of superior results in technique to the practical microscopist and also affording an incentive and inducement for better and increased action. His advancement beyond many others in the profession was indicated by the prizes, medals, honorable mentions and scientific distinctions that were conferred upon him. In 1865 he was given a diploma as an award for merit form the Massachusetts Charitable Mechanical Association and nine years later a similar diploma came from Franklin Institute of Philadelphia. The receipt of the Elliott Cresson gold medal on the 18th of January, 1875, which was intrusted to the recommendation of the Franklin Institute by the provision of the founder's will, was an indication of the marked superiority of general workmanship and finish; the improved plan of setting the binocular prism; the introduction of a circular rotating and concentric stage; the plan by which exact amplification of the image in the binocular instrument is obtained; the invention of a direct vision-erecting prism; the improved and perfect (mark the word "perfect") mechanical finger; the optical superiority of the lenses ("the lenses have no superiors"); and lastly, "for the erection and conduct of an optical establishment in our own city wherein work equaling the best done abroad is done on principles of honesty and through mechanical skill; and all this as the result of one unaided individual." In recognition of the same points the Franklin Institute conferred upon him a silver medal. When a bronze medal for microscopic stands was bestowed upon Mr. Zentmayer by the United States Centennial Commission for Swards at the international exhibition held in Philadelphia in 1876, it was given for "superiority of workmanship, rigidity and freedom from tremor and the convenient arrangement of their moving parts as unsurpassed by any in use," to which was added: "Besides the forms already familiar to microscopists he has presented one which is substantially new and which embodies a number of important improvements. This exceedingly ingenious stand is in every important respect original with the exhibitor and is presented as a characteristically American stand. The objectives of three-inch focus, one and one-half-inch, eight-tenths-inch, one-half-inch, one-fourth-inch and one- fifth-inch are not surpassed in defining power by those of any other maker." "The resolving power of the one-fourth and one-fifth-inch is also remarkable." For a pocket microscope which folds up without separation of parts into a case, which when in use forms its stand and is small enough to be carried without inconvenience in the coat pocket." "For an admirable dissecting microscope, furnished at a low price." "Further, of the numerous forms of apparatus accessory to microscopic observations, exhibited by Mr. Zentmayer, may be mentioned as especially worthy of commendation, a very ingenious erecting prism, a mechanical finger for picking up and arranging diatoms and other minute objects, etc.

In a memorial written by Charles A. Oliver further mention of Mr. Zentmayer's high scientific attainment was made as follows: "To this stand he added a most important arrangement, without which no microscope can be considered complete. This consisted in a swinging substage which, while carrying an achromatic condenser or illuminating apparatus, held a mirror which swung around a pivot placed behind the stage, of which the axis passed through the object observed, so that the object is in the focus of the illumination in every position. This remarkably ingenious plan of swinging the substage and the mirror so as to have the object as its center, induced numerous foreign and domestic makers to employ this important principle in optical construction. Two years later a third and most important honor was added to the list by the committee of awards on microscopes at the Paris Exposition, who found fit to give a silver medal and a diploma to Mr. Zentmayer for the superiority, manifold value and simplicity of his workmanship.

Recognizing the value and convenience of the Abbe system of condensing lenses or illuminator in stands that are provided with substages, he modified the ordinary form by so placing the carrier that the diaphragms can be readily changed and arranging the contrivance so that the diaphragm cannot only be moved over the field by rack and pinion but that it can be revolved. How much we must praise his exquisitely simple, single-prism, total-reflecting camera lucida which is so contrived as to be used either in the upright, angular or horizontal positions of the draw-tube of the microscope. How exasperatingly easy of comprehension and yet how excellently adapted for their purpose are his contrivances of the life-current and siphon-slides so arranged in accordance with Mr. S. D. Holman's ideas that varying degrees of circulation in animalculae can be made visible, not only to the individual student at work with his highest powers, but actually made recognizable to large audiences during class-work instruction and lecture-room demonstration. Again, the wonderful mechanical construction of Professor John A. Ryder's automatic microtome where, with an ordinary razor, tissue-sections of .0025 millimeters thickness can be cut by the merest novice, and objects to the length of fifteen centimeters and two centimeters wide can be completely cut serially into almost any desired thickness. Further, the botanical dissecting microscope designed and constructed to meet the requirements of professor J. T. Rothrock, of the University of Pennsylvania, (a member of this society), in his botanical class; his clinical stand for accurate examination of any object by a large class, by being passed from hand to hand, that the memoirist has so often used in his student days; the cheapening and simplification of the microscope so as to bring a properly constructed and adequately working piece of apparatus into the hands of the student of limited means, thus allowing him to become an essential factor in scientific progress; these few contrivances are but a limited number of the mechanical triumphs that resulted form the employment of the never-ceaseless mind of Joseph Zentmayer (the optician) as he proudly styled himself, for more than a half century. Is it any wonder that we exclaim with Von Humboldt, "In the moral world there is nothing impossible if we bring a thorough will to it. Man can do everything with himself.

An interesting incident in his life is the history of the patent of his doublet photographic lens, which is composed of two deep meniscus lenses with their convex sides placed outwardly. He made the outer meniscus one-half larger than the back lens, thus allowing six different combinations with seven single lenses. Such a lens having an angle of nearly ninety degrees and great depth of focus, and giving extreme sharpness over the whole field and being free from all distortion, necessarily became a most excellent instrument for architectural work and copying. The story of the invention is this: One year before the patent of the lens was obtained Mr. Coleman Sellers, who was at that time greatly interested in photography, requested Mr. Zentmayer to explain the theory of the then favorably known 'Globe lens.' Whilst examining a sample of the lens Mr. Zentmayer remarked, "Why did the inventor adopt an achromatic combination when the same or even better results could have been obtained by the combination of two simple meniscus lenses?" Recognizing the force of the query Mr. Sellers requested Mr. Zentmayer to experiment with a double lens. This having been successfully accomplished he urged him to apply for a patent which was reluctantly agreed to and done after the most earnest solicitation. The introduction of this lens engendered a most spirited controversy as to question of the theory in optics involved in its construction. Professor Henry Morton, Dallmeyer and other well known authoritative scientists and experts, both here and abroad, took part in this discussion. Mr. Zentmayer's personal appearance in the matter, which showed itself in a short article entitled 'Refraction without Dispersion and some Reflection.' in the August, 1867, number of the Philadelphia Photographer, proved at once in a most forcible and logical manner that the writer was a consummated master in the field of theoretical and applied optics -- a paper that immediately established him as America's foremost optician.

One monograph, as further illustrating the remarkable clearness, ease of expression and fullness of comprehension with which eh surrounded one of the most abstruse and most readily misunderstood of the theoretical and applied sciences -- optics -- is his illustrated brochure of twenty-three pages entitled 'A Lecture on Lenses.' This, which appeared in the May and June, 1876, numbers of the Journal of the Franklin Institute , is even now authoritatively recognized as one of the best, the most concise and the clearest exposition of the subject that has ever been presented to the public.

Engaged as the official maker of the microscopes used in the hospitals of the United States Army; appointed a member of the Iowa Total Eclipse Exhibition in 1869, to the success of which he contributed largely by the device of some of the most delicate of the photographic machinery; a member of the judge of awards in the 1874 fair of the Franklin Institute, the International Centennial Exhibition in 1876 and the Electrical Exhibition in 1885; a life-member of the German Hospital, and a member of the American Philosophical Society, the Academy of the Natural Sciences of Philadelphia, both the American and British Associations for the Advancement of Science, the Franklin Institute of Philadelphia, both the American Society and the New York Society of Microscopists, the Biological and Microscopical Society of Philadelphia, the Philadelphia Kunstlerverein, we can well see that not only was his public work of the most varied character, the most useful to both his city and his country, and of the most value to science, but that his associations were the widest, the most congenial and the most elevating in character.

It is seldom that one expects to find the scientific nature supplemented by and combined with a love of literature and the arts. Mr. Zentmayer, however, had as his constant companions in his leisure hours the works of the eminent writers of Germany, of England and of America, notwithstanding the fact that he mastered the English language after he had attained manhood. He had the German love and appreciation of music and equal enjoyment in painting and sculpture. He belonged to many societies that cultivate an appreciation for all the ennobling influences of life and it is said that in his own home there were evidences not only of his exceptional taste in these, the pleasures of higher mental life, but that these evidences also exhibited his acumen and practical judgment in their enjoyment.

Above and beyond all that made Mr. Zentmayer an eminent scientist, the critic and patron of the arts, he was a man of those high moral qualities which find their manifestation in justice, truth, loyalty and honor. To his friends - - and he gathered about him a select circle of eminent men -- he was evermost faithful. Good nature and modesty were strongly marked characteristics and though he attained to eminence he had the highest appreciation for what others were doing and had done to contribute to the world's progress. Death came to him on the 28th of March, 1888, but his contribution to the world's work will make his name honored for years to come, while his memory is sacredly cherished by those who knew him in the intimate ties of friendship.