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."