John Gregory’s Adaptation of Maksutov’s Design, Patent Constraints, and Braymer’s Location of the Questar Telescope’s Secondary Spot
Over the course of my research, I have encountered several accounts that characterize John Gregory as the holder of the patent that compelled Lawrence Braymer to locate the aluminized secondary spot on the less efficient outside (R1) surface of the corrector lens rather than on its more favorable inside (R2) position. I believe, however, that these accounts are mistaken. Rather, it was a patent held by Albert Bouwers, Johannes Becker, and Adriaan Hendrik van Gorum and licensed to the Wollensak Optical Company of Rochester, New York that forced Braymer’s design decision.
Numerous sources may lead one to believe the contrary. As an addendum to John Gregory’s March 1957 article in Sky and Telescope, “Gleanings for ATM’s” columnist Robert E. Cox added that Gregory was “a mechanical engineer working on optical system development at the Perkin-Elmer Corp., Norwalk Conn. He has provided the above details of his designs for amateur use only; the Perkin-Elmer Corp. retains all commercial rights.”[1] What Cox did not do was indicate the specific legal instrument through which Perkin-Elmer retained those rights.
Secondary accounts also contain a proliferation of claims that John Gregory designed and patented a variation of the Maksutov-Cassegrain telescope.
In his Public Skies: Telescopes and the Popularization of Astronomy in the Twentieth Century, for instance, Gary Leonard Cameron wrote that attendees at the August 1956 Stellafane gathering “could actually inspect a small Maksutov telescope at the meeting, one built by an amateur telescope maker named John Gregory, who would later, as a professional optician, go on to patent the Gregory-Maksutov design.”[2] Cameron does not cite the patent that Gregory held, however.
The writer of Wikipedia’s article on Questar Corporation makes the most explicit link between John Gregory’s legal claims and Lawrence Braymer’s design decisions. This account indicates that, “to avoid a conflict with a design patent held by John Gregory licensed to Perkin-Elmer, Braymer put the secondary spot on the outer (R1) surface of the corrector lens.”[3]
In support of this assertion, that writer then cites an article appearing at telescope-optics.net:
[The] first published telescope arrangements in the U.S. that followed the 1941 introduction of [a] full-aperture meniscus corrector for [a] spherical mirror was a pair of two-mirror Cassegrain systems—ƒ/15 and ƒ/23—and [a] Maksutov-type corrector by John Gregory in 1957. In it, the secondary was an aluminized spot at the back surface of the corrector. At the time, Lawrence Braymer was already producing his famous-to-be Questar Maksutov-Cassegrain, a design very similar to Gregory’s (in order to avoid patent infringement, Questars had—for about a decade—the aluminized spot placed at the front meniscus surface).[4]
The author of Wikipedia’s article on Questar Corporation seems to have misread the account at telescope-optics.net. The latter identified John Gregory’s article entitled “A Cassegrainian-Maksutov Telescope Design for the Amateur,” which appeared in the March 1957 issue of Sky and Telescope. Content at telescope-optics.net also correctly points out that the Questar telescope was already in production by the time Gregory’s article appeared and that Lawrence Braymer’s design decisions were indeed constrained by patent considerations, although the article does not identify the exact patent that was responsible for this. On the other hand, the writer of the Wikipedia article on Questar Corporation conflates the motivating factors behind Braymer’s design actions with Gregory’s accomplishments and whatever intellectual property claims he may have made. The author behind the telescope-optics.net article, in other words, draws no link between Gregory and Braymer.
Other content on Wikipedia adds to the confusion. In its article on the Maksutov telescope, Wikipedia indicates that Maksutov’s design “appeared commercially in Lawrence Braymer’s 1954 Questar telescope and in Perkin-Elmer designer John Gregory’s competing patent for a Maksutov-Cassegrain. Commercial use of Gregory’s design was explicitly reserved for Perkin-Elmer but was published as an amateur telescope design in a 1957 issue of Sky and Telescope in a f/15 and f/23 variation.”[5] As John Gregory’s March 1957 Sky and Telescope article pointed out, restrictions on using his design did not apply to use by amateur telescope makers (ATMs), and the Wikipedia article on the Maksutov telescope correctly indicates the commercial restriction. But Wikipedia again makes a muddle of this issue by propagating the notion that there was a “competition” between Braymer’s design and that of Perkin-Elmer employee John Gregory without actually drawing a direct link between whatever patents that Gregory or Perkin-Elmer held, on one hand, and the design decisions that Braymer made before bringing the Questar telescope to production, on the other hand.
Who first developed the design that featured a secondary spot that was directly aluminized onto the inside surface of the corrector lens? At least two commentators identified John Gregory as the inventor of this design. In his Buyer’s and User’s Guide to Astronomical Telescopes and Binoculars, James Mullaney wrote:
In a modification of [Maksutov’s] scheme known as the Gregory-Maksutov and invented by John Gregory in 1957, the secondary mirror is actually an aluminized central spot on the back surface of the meniscus itself. Many instruments marketed today as Maksutov-Cassegrains actually use this system and are, therefore, technically Gregory-Maksutovs.[6]
John F. Gills also wrote that Gregory:
developed further refinements in the Maksutov-Cassegrain design. Most notably he did away with the separate secondary mirror and replaced it with a mirrored spot on the corrector shell itself. This brings us to the modern instrument which could be called the Gregory-Maksutov-Bouwers-Schmidt-Cassegrain-Gregory telescope, but which most people simply call the “Mak.”[7]
Neither Mullaney nor Gills give Bouwers credit for the idea of applying the secondary mirror spot directly to the rear surface of the corrector lens.
But U.S. patent #2,504,383, which Albert Bouwers and his colleagues filed in December 1945 and was granted in April 1950, quite clearly describes a “convex collecting mirror” that “consists of the central part of the convex corrector surface facing the main mirror, which central part is coated with a reflecting layer of aluminium.”[8] The secondary mirror, in other words, was characterized precisely as an aluminized coating that was applied directly to the inside surface of the corrector lens.
The last critical piece fell into place, according to collector Stewart Squires, when Bouwers licensed his patent to the Wollensak Optical Company in the United States. It was this legal arrangement that compelled Braymer’s decision to locate the Questar’s secondary spot on the outside surface of the corrector lens.[9] Considering his deep and authoritative knowledge of Questar’s early history and his own direct contact with primary source documentation, I believe that Squires’s account is trustworthy and accurate.
Another question remains unanswered: what specific patents did John Gregory file and hold, and which of these had any effect on the final design for the Questar telescope? To be sure, the absence of evidence does not prove it does not exist. But Gregory’s supposed patent that a number of writers identify has yet to surface. Optics patent attorney Ben Langlotz wrote in March 2019, for instance, that he has “searched in vain trying to find that patent that people speak of.”[10]
On the other hand, there is no question that Bouwers’s U.S. patent #2,504,383 exists. Moreover, Lawrence Braymer directly cited it in his own U.S. patent #2,670,656, which he filed on November 25, 1947, and was issued on March 2, 1954.[11] Braymer even acknowledged both Maksutov and Bouwers in his illustration of telescope designs that had emerged through the ages that he included as part of his Questar promotional booklet of 1954.[12] Nowhere did he give any credit to John Gregory.
Beyond the issue of the missing Gregory patent, there is also simple chronology to consider. John Gregory, who was born in 1927, would have been completing his undergraduate work or commencing his graduate studies at the age of twenty-two in 1949, when Braymer’s patent attorney Joseph Denny suggested relocating the secondary spot of his client’s new telescope to the outside surface of its corrector lens.[13] Although Gregory may very have been an optical design phenom early in his life, the possibility that he not only conceived of a design but was also issued a patent for it in time to roadblock Braymer’s progress in 1949 seems unlikely.
Although the point in time at which he conceived of his design is an open question, there is no doubt that John Gregory exhibited it at the Stellafane convention in August 1956 and that he published an account of his work in his now famous article that appeared in the March 1957 issue of Sky and Telescope. But these events occurred more than two years after Braymer began marketing the Questar telescope in 1954 and well after Braymer began his design work in the mid- to late 1940s. Whatever patent John Gregory may have actually been granted might have further complicated matters for Braymer. But this possibility seems implausible if the Questar telescope had already been in production by the time Gregory received any patents for his design work.
In light of all this, I argue that the legal constraint that forced Braymer to move the placement of Questar’s secondary spot to the R1 position of its corrector lens was not a patent held by John Gregory and licensed Perkin-Elmer. It was instead the U.S. patent held by Albert Bouwers and his colleagues and licensed to the Wollensak Optical Company of Rochester, New York.
Notes
1 Robert E. Cox, “Gleanings for ATM’s,” Sky and Telescope, March 1957, 238.
2 Gary Leonard Cameron, “Public Skies: Telescopes and the Popularization of Astronomy in the Twentieth Century,” PhD diss., (Iowa State University, 2010), 246-247, https://lib.dr.iastate.edu/etd/11795/, accessed September 30, 2019.
3 “Questar Corporation,” Wikipedia, n.d., https://en.wikipedia.org/wiki/Questar_Corporation, accessed December 29, 2019.
4 “Maksutov-Cassegrain Telescope,” Notes on Amateur Telescope Optics, n.d., https://www.telescope-optics.net/maksutov_cassegrain_telescope.htm, accessed December 29, 2019.
5 “Maksutov telescope,” Wikipedia, n.d., https://en.wikipedia.org/wiki/Maksutov_telescope, accessed December 29, 2019.
6 James Mullaney, A Buyer’s and User’s Guide to Astronomical Telescopes & Binoculars (London: Springer, 2007), 47, https://books.google.com/books?id=hzpoQRh9QEQC&pg=PA46#v=onepage&q&f=false, accessed June 17, 2020.
7 John F. Gills, “From James Gregory to John Gregory: The 300 Year Evolution of the Maksutov-Cassegrain Telescope,” weasner.com, 1998, http://www.weasner.com/etx/guests/mak/MAKSTO.HTM, accessed December 29, 2019.
8 Albert Bouwers, Johannes Becker, and Adriaan Hendrik van Gorum, 1950, Reflecting Type Telescope Having a Spherical Mirror, U.S. Patent 2,504,383, filed December 18, 1945, and issued April 18, 1950, https://patents.google.com/patent/US2504383, accessed December 29, 2019.
9 Stewart Squires, email message to author, October 28, 2019.
10 Ben Langlotz, online forum posting, Cloudy Nights, March 7, 2019, https://www.cloudynights.com/topic/653162-an-observing-quirk-with-early-questar-scopes/?p=9197886, accessed January 1, 2021.
11 Lawrence Braymer, 1954, Telescope, U.S. Patent 2,670,656, filed November 25, 1947, and issued March 2, 1954, https://patents.google.com/patent/US2670656, accessed December 29, 2019.
12 Questar Corporation, Questar booklet, May 1954, 18.
13 “John F. Gregory,” Wikipedia, n.d., https://en.wikipedia.org/wiki/John_F._Gregory, accessed January 1, 2021; “Questar Products Index & Overview Page,” Company Seven, n.d., http://www.company7.com/questar/index.html, accessed November 3, 2019.