NEW FORMS OF TELESCOPES.

{Achromatism} and other forms of optical instruments

To the Editor of

            Sir,

                        There have recently appeared in the newspaper and scientific press communications dealing with a new form of telescope combining the optical principles of reflectors and refractors in such a way as to secure cheap, achromatic instruments of about half the usual focal length {The fundamental principle of which consists in attaining the achromatism of a large Object-Glass by the interposition of a small concavo-convex lens, silvered on the back. The curvatures of the small correcting negative lens with its internal reflecting surface being so proportioned as to cause its negative chromatism  to destroy[?] the positive chromatism of the object glass in  a more perfect manner than has yet been attained in a refractor; at the same time at a much less cost and ^with a shorter tube}.

                        It has recently been announced the Professor Schupmann, of the Technische Hoch Schule  at Aix la Chapelle in Prussia {on July 30/97 applied for and} has in the United States, under Letter Patent No.620978, dated March 14^th, 1899, patented such an instrument as is above described, under the name of “Medial-Fernrohr ,” and that the combination used is equally applicable in the case of microscopes and photographic-cameras. Among other things, it is claimed that one of the advantages of the telescope is that single crown glass lenses alone may be used {Prof Schupmann it is also announced ^has published a book on the subject}.

                        Under the circumstances, and in defence of the interests of two of its members, Messrs. Z.M. and J.R. Collins, The Astronomical and Physical Society of Toronto thinks it proper to intervene, for the purpose of laying before your readers certain facts not hitherto

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published, and which may tend to place the alleged new invention in a different light.

                        In 1893, the Messrs. Collins invented and patented ^constructed a Telemeter {of their own design, in which a modified form of dialyte objective was used for the purpose of shortening the tube and amplifying the focus}.  As a further result of their studies, they came to the conclusion that the ^certain principles employed in their Telemeter might be advantageously used in a telescope combining some of the properties of a refractor and a reflector. In the summer of 1896, they constructed ^completed and exhibited privately to a few friends ^{and a number of members of this Society} an four-inch instrument {of 4ⁱⁿ aperture, 2 ft in length and 4 ft focus} which they called the “Monoplane ^Achromatic Telescope.” This instrument performed admirably, ^{photographs being taken with it}and it seemed to be so satisfactory that a couple of friends offered to join them in patenting it and placing it upon the market. On the suggestion of the Messrs. Collins, however, who felt that the invention would be received with more confidence if they were able to secure the approval for it of well-known scientific men, highly confidential communications were, in the spring of 1897, addressed to Lord Kelvin, and to Professor J.A. Brashear, of Allegheny, Pa., and Dr. H.C. Vogel, Potsdam, Prussia. To these gentlemen were also submitted drawings as well as descriptions of the invention ^{fundamentals of the monoplane combination}. On the date before him, Lord Kelvin declined, however, to express a conclusive opinion; Professor Brashear, while not committing himself to the principle involved, suggested that an eight-inch telescope of high quality should be constructed and

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tested. In his first communication, Dr. Vogel, who stated that he had shown the invention to his assistants, unsparingly condemned the telescope. But after a letter explaining to him certain points which he had apparently misconceived, he stated that it appeared to have many merits. As a result, the Messrs. Collins ordered, in Rochester, N.Y.,  [this may have been Bausch & Lomb] the necessary lenses, but, for reasons which need not be mentioned, one delay succeeded another, and it was only recently that it was found feasible to take the necessary steps towards patenting the device, the excellence of which had now received a practical demonstration. [portions of this expunctuated passage may have been reinstated; there are also interlinear additions, and very faint marginal additions both in pencil which are difficult to construe].

                        The point which the Society wishes to make is that, so long ago as the summer ^{early part} of 1896, a telescope almost precisely the same as ^{embodying the structural practices of} that now described by Professor Schupmann, was constructed and tested in Toronto. In his annual address to the Society, delivered on the 12th of January, 1897, Mr. J.A. Patterson, M.A., President, referred to the instrument, and claimed for the Society the credit of having members sufficiently skilled in optics to produce a new combination of lenses composed of one kind of glass, which could be used for telescopes, microscopes and cameras, greatly cheapening the cost and reducing the size of those instruments.

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                        It may be added that upon this subject the Society is preparing a special report which will include copies of the correspondence which passed between the Society and the parties referred to, and affidavits verifying the facts therein mentioned.

                        In justice to the Messrs. Collins, I am to ask you to be so good as to find room in your valuable paper for this communication.

This document concerns an interesting priority dispute about the invention of a very-well corrected catadioptric optical system, now known as the Schupmann Medial telescope, one of the class of tilted-component telescopes; G.H. Smith, R. Ceragioli, & R. Berry, Telescopes, Eyepieces, Astrographs: Design, Analysis and Performance of Modern Astronomical Optics (Richmond, VA: Willmann-Bell, 2012), pp. 332-333, 361-369. A recent ATM monograph devoted to the designs is J. Daley, The Schupmann Telescope (Richmond, VA: Willmann-Bell, 2007). The design excels for solar and planetary work. The largest professional instrument capable of operating as a Schupmann is the  Swedish 1-m Solar Telescope (SST) on the island of La Palma, Spain. A notable amateur installation is the recent 13" Schupmann of the McGregor Observatory at Stellafane (built 1987-1994), which in turn is dwarfed by the imposing Rathenow Brachymedialfernrohr (a design similar to the "Schupmann") with it's 0.7m (27.56") O.G. constructed by the amateur astronomer Edwin Rolf (1899-1991) in 1949-1953; the Rathenow Brachymedialfernrohr was restored in 1994-1996.

For all of the effort the Toronto Astronomical Society (TAS, predecessor of the RASC) spent on defending the Collins brothers' claim to prior invention, or co-invention, the design is now known by the German optician's name alone. None of the standard modern histories on astronomical optics mention the Collins brothers, or even acknowledge that there was a dispute; e.g., H.C. King, The History of the Telescope (London: Chas. Griffin & Co., 1955); R. Riekher, Fernrohre und ihre Meister (Berlin: Verlag Technik GmbH, 1899). It should be noted that W.F. Hamilton (UK) in 1814 patented a form of telescope with a tilted Mangin element in a front-view arrangement, forshadowing aspects of Schupmann's design (I owe this reference to the kindness of Dr. Roger Ceragioli; private communication 2013 June 22).

It is clear that the TAS felt honour-bound to defend the priority of its members' invention, as recounted in the minutes of the Society's meeting of 1900, September 18, printed in the Transactions of the Toronto Astronomical Society for the Year 1900 (Toronto: Carswell Co., Ltd., 1901), 30:

The Corresponding Secretary, Mr. W.B. Musson, stated that he had sent authorized communications to several scientific periodicals in explanation and support of the claim of the Messrs. Z.M. and J.R. Collins to the invention by them of monoplane telescopes, the first of which had been constructed and exhibited, as members of the Society knew, so early as the spring of 1896. These communications had been drawn up by the special committee consisting of Mr. J.A. Paterson, Chairman, the President [G.E. Lumsden, FRAS] and Messrs. A. Harvey, J.R. Collins and himself [W.B. Musson]. Documentary evidence of a perfectly satisfactory character had been procured and was available for use whenever required [such a dossier, presumably containing the letters of Brashear, Lord Kelvin, and Prof. Vogel, does not survive in our Archives].

Musson's draft at the head of this article was the literary starting point for the TAS' information campaign, resulting in at least three "authorized communications". The text of that which apperaed as New Forms of Telescopes and other Optical Instruments in The Observatory, 23 (1900), 350-352 is as follows:

New Forms of Telescopes and Other Optical Instruments.

Gentlemen,―

            There have recently appeared in the newspaper and scientific press communications dealing with a new form of telescope, the fundamental principle of which consists in attaining the achromatism of a large object-glass by the interposition of a small concavo-convex lens, silvered on the back―the curvatures of the small correcting negative lens, with its internal reflecting surface, being so proportioned as to cause its negative chromatism to correct the positive chromatism of the object-glass more completely than has yet been attained, at the same time at a much less cost and with a shorter tube.   

            It has recently been announced that Professor Schupmann [1851-1920], of the Technische Hoch Schule at Aix-la-Chapelle, in Prussia [now Aachen in Nordrhein-Westfalen, Bundesrepublik Deutschland], on July 30, 1897, applied for and obtained in the United States (under Letters Patent No. 620978, dated March 14th, 1899) a patent on such an instrument as is described, under the nome of “Medial-Fernohr [sic].” Among other things it is claimed that one of the advantages of the telescope is that single crown-glass lenses alone may be used. Prof. Schupmann, it is also announced, has published a book on the subject [this appeared as Ludwig Schupmann, Die Medial-Fernrohre (Leipzig: B.G. Teubner, 1899)].

            Under the circumstances, and in defence of the interests of two of its members, Messrs. Z.M. and J.R. Collins, the Toronto Astronomical Society thinks it right to intervene for the purpose of laying before your readers certain facts not hitherto published, and which may tend to place the alleged new invention in a different light [on the Collins brothers, see p. 71 of Peter Broughton's Looking Up].

            In 1893 the Messrs. Collins constructed a Telemeter of their own design in which a modified form of dialyte objective was used for the purpose of shortening the tube and amplifying the focus [in the late-Victorian world the term “telemeter” could designate a rangefinder, and a dialyte was an objective with separated elements]. As a further result of their studies they came to the conclusion that certain principles employed in their Telemeter might be advantageously used in a telescope combining some of the properties of a refractor and a reflector. In the summer of 1896 they completed and exhibited to a few friends and a number of members of this Society an instrument of 4 inches aperture, 2 feet in length, and 4 feet focus, which they called the “Monoplane Achromatic Telescope” [in none of the surviving correspondence is the term "monoplane" explained; it is a curious choice]. This instrument performed admirably, photographs being taken with it [we have not been able to ascertain if any survive]. On the suggestion of the Messrs. Collins, confidential communications were, in the spring of 1897, addressed to Lord Kelvin, and to Prof. J.A. Brashear, of Alleghany, Pa., and Dr. H.C. Vogel, Potsdam, Prussia [now the capital of Brandenburg, Germany. All three men were outstanding professionals in their scientific disciplines, and Brashear and Vogel were honorary members - unfortunately their letters in response to this query have not survived in our Archives]. To these gentlemen were submitted drawings as well as descriptions of the fundamentals of the Monoplane combination. On the data before him Lord Kelvin declined, however, to express a conclusive opinion; Prof. Brashear, while not committing himself to the principle involved, suggested that an 8-inch telescope of high quality should be constructed and tested. In his first communication Dr. Vogel, who stated he had shown the invention to his assistants, unsparingly condemned the telescope. But after a letter explaining to him an error in the figures first supplied him, together with enlarged explanations, Dr. Vogel then said the combination appeared to him in an entirely new light, and with the figures then before him he found the correction for chromaticism “to be more complete, indeed, than is the case with the ordinary achromatic objective.”

            As a result the construction of an instrument of 8 inches aperture was proceeded with, the late President, Mr. Arthur Harvey, F.R.S.C., and Mr. John M. Martin joining them with a view to furthering its completion. The development, however, of an important feature of the combination (not mentioned in the communications referred to and not included in Prof. Schupmann’s patent specifications) delayed the construction of the second instrument, and it was not until this was nearly completed that Prof. Schupmann’s patent proceedings became known.

            The point which the Society wishes to make is that, so long ago as the early part of 1896, a telescope embodying the essential features of that described by Prof. Schupmann was constructed and tested in Toronto. In each of two annual addresses to the Society delivered in January in each of the years 1896 and 1897, Mr. John A. Paterson, M.A., President, referred to the instrument and claimed for the Society the credit of having members sufficiently skilled in optics to produce a combination of lenses composed of one kind of glass, which could be used for telescopes, microscopes, and cameras, greatly cheapening the cost and reducing the size of these instruments.

            In the address of 1896 he says:―“The Collins Brothers have proved their ability in the figuring and polishing of parabolic mirrors for reflecting telescopes, and recently they have invented a telescope of an entirely new design, which will attain a maximum result at a minimum cost, measuring only half the length of the ordinary design, bearing at the same time the same magnifying-power and possessing the virtue of achromaticism by the use of two lenses, both of crown glass. By changing the relative position of the chief lenses the achromaticism can be under-corrected or over-corrected. A short achromatic telescope with two lenses of the same material sounds like an impossibility.”

            In the address of 1897 he says:―“Two of our most earnest members, the Collins Brothers, are still developing their new Monoplane Achromatic Telescope. It is one of 8 inches aperture, having a new form of objective of one kind of glass. Mounted equatorially it delivers an image of a celestial object in front of the eyepiece in dimensions equivalent to a length of 40 feet, although the extreme length of the instrument complete is but 4 feet. It is able to correct for spherical aberration as well as chromatism and also for the ‘Schaeberle’ aberration that must necessarily exist in the ordinary refractor of great angular aperture [Musson is in error;  Schaeberle’s aberration occurs in parabolic mirrors caused by the focal point of the image not coinciding with the centre of curvature of the reflecting surface; also see Schaeberle's fuller treatment]. Dr. H.C. Vogel, of the Astrophysical Observatory, Potsdam, after a mathematical analysis of the correction for achromaticism, says, ‘a workable objective is now shown which, as the reasoning proves, unites in an excellent manner the rays from red to violet, better indeed than is the case with an objective of the usual construction.’ It may be added that the same principle may be applied to the microscope.”

            Upon this subject the Society is preparing a special report, which will include copies of the correspondence which passed between the Society and the authorities referred to [unfortunately, it never appeared].

            In justice to the Messrs. Collins, I am to ask you to be so good as to find room in your valuable magazine for this communication.

W.B. Musson

In addition to the above letter placed in The Observatory, an identical piece appeared in The English Mechanic & World of Science 1849 (August 31, 1900), 61, and a marginally more technical version was published in Knowledge, 1900 November 1, 252, a periodical which began life as Richard Proctor's rival publication to Norman Lockyer's Nature. Among the differences between the printed texts and Musson's draft, the most interesting may be the removal of any reference to the Collins brothers' efforts to seek formal patent protection.

It was the contribution to the English Mechanic & World of Science (EM&WS) which mattered most, for the story and its denouement are be found in its pages. It's not surprising the dispute was waged there, for the EM&WS was arguably the most significant English-language periodical for serious amateur discussion of astronomy (Popular Astronomy founded in 1893, out of Carleton College, Northfield MN, had yet to establish its dominance in the field).

Prof. Schupmann's response to Musson in the EM&WS 1856 (Oct. 19, 1900), 229-230, reads as follows:

THE “MEDIAL” TELESCOPES.

Number 1900 of the “E.M. [English Mechanic & World of Science],” p. 61, contains a communication by Mr. W.B. Musson, secretary of the Toronto Astronomical Society, in which Mr. Musson appears to claim priority of the invention of a new kind of telescope, called by me “Brachymedials,” not for me, but for two members of his society, Messrs. Z.M. and T.R. Collins, of Toronto.

He did not think fit to favour me with a copy of the said communication, and it was by a mere accident that I became acquainted with it. As the drift of Mr. Musson’s communication may be misunderstood, I think it right to submit to scientists the following facts, fearing that silence on my part might be misinterpreted.

1. The various kinds possible of the new instruments and the conditions of removing the secondary spectrum in the same, were found out by me as a result of numerous minute calculations as early as the year 1892―that is, at the time when Messrs. Collins were not yet thinking of the construction of such an instrument [our emphasis]. In 1893, that is to say, three years before Messrs. Collins, I put together the first “Brachymedial,” as may be read in my book published in the beginning of 1899. The two lenses necessary for the purpose (a single plane convex objective lens and a smaller concave meniscus) I had already purchased from Herr Venneman, optician at Aix-la-Chapelle, before the end of 1892.

2. Regarding “confidential communications” to competent gentlemen, to which Mr. Musson seems to attribute great importance, in that respect also I forestalled Messrs. Collins. While the latter first communicated their idea to Lord Kelvin, Prof. Brashear, and to Prof. Vogel in May, 1897, I had already laid my complete theory before Prof. W. Wien (the successor of Roentgen at Wuerzburg), in November, 1896―that is to say, fully six months earlier. Prof. W. Wien entirely approved of my theory, and encouraged me to proceed with the construction of a “medial.” The two small concave meniscuses, which are a most characteristic part of the invention, were ordered from the firm of Voightländer u. Sohn, at Braunschweig, as early as April 12, 1897. The whole instrument was finished by June, 1897.

3. This “medial,” the most valuable type of the new instruments (in which the light reaches the concave correcting system and the concave mirror surface after having passed through a prism placed close to the focus of the object-glass) has not been hit upon by Messrs. Collins at all.

4. And last, I desire to call attention to a fact, compared with which those mentioned above are of slight significance. The only publication referring to the subject has been by me. (“Die Medial Fernrohre,” Leipzig, B.G. Teubner, 1899). Now it is a custom universally prevalent among scientists that the priority of a discovery belongs scientifically to him who first publishes in a scientific manner the principle and details of an invention. Nothing of the kind has been attempted by Messrs. Collins. The addresses to the Astronomical Society of Toronto are anything rather than publications of the invention. The most essential part of the invention, the concave mirror surface, has not been so much as hinted at in the addresses.

            While unable to admit Messrs. Collins's claim to priority, I have no hesitation in acknowledging that they have later than I, but quite independently, discovered the less valuable type, the "Brachymedial [our emphasis]." In conclusion, I should like to know what the improvement which Messrs. Collins claim to have made in the Brachymedial consists in [the Collins brothers never responded to this reasonable request in these pages].

            It may interest the readers of the ENGLISH MECHANIC that since June 5, 1900, a Medial "of 12in. aperture and 15ft. focal length" has been placed in the "Urania" Observatory at Berlin. The instrument was constructed according to my calculations by the well-known firm of Reinfelder u. Hertel at Muenchen. The instrument produces entirely achromatic images even of the brightest celestial objects. Double stars of 0.6 [arc second] distance, as, for example, χ Aquilae, are separated by it without any difficulty.

            I hope you will give me a chance of stating my case to your readers by publishing this letter in your valuable paper. Prof. L. Schupmann.

Aix-la-Chapelle, Oct. 10.

In the eyes of the international astronomical community, Prof. Schupmann's account settled the matter of priority, and handily established who had the better theoretical understanding of the optics involved. Prof. Schupmann's letter may have been the factor which put an end to any thought of the TAS producing a pamphlet setting forth their priority claims for the Collins' "Monoplane Achromatic Telescope" (if such a pamphlet was produced, it has left no trace in our Archives). It is unfortunate that the Collins brothers and the leadership of the TAS hadn't had a chance to consult Prof. Schupmann's monograph before Musson officially communicated with the astronomical world. Had they done so, aspects of that communication may have been different. Features of the Schupmann Medial telescope were discussed further in that year's numbers of the EM&WS, but the discussion entirely ignored the Toronto contribution. Prof. Schupmann showed commendable generosity in stating that he had "no hesitation in acknowledging that they [the Collins brothers] have later than I, but quite independently, discovered the less valuable type, the "Brachymedial"". The verdict of history, for what it is worth, seems to have been less generous.

The fairest assessment of the evidence presented here is that both the Canadian and the German opticians independently and concurrently invented tilted-component telescopes with striking similarities.

 

—R.A. Rosenfeld, RASC Archivist (2013)

Acknowledgement: the author wishes to thank Peter Abrahams and Dr. Roger Ceragioli of the Antique Telescope Society for useful comments, and Walter MacDonald for the work of digitizing. Any errors remaining are due to the author (R.A.R.) alone. This research has made use of NASA's Astrophysics Data System.