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My collection of Grubb Patent Aplanatic Lenses made in Dublin between the 1850s and the 1870s all have micro-engraving with a number at the very edge of the glass lens element to match the engraved or stamped number on the brass barrel of the lens. The purpose behind this is to indicate authenticity and avoid fakes.The writing (for that is what it is) is barely visible to the naked eye and even more difficult to photograph.
Below is a poor photo of the micro engraving on the lens element of Grubb Patent Aplanatic No 582 which reads 'Grubb Patent No 582'. No 582 is the lens in the front middle of the group photo of my Grubb lens which is also below.
What I am wondering is whether other 19th Century lens manufacturers 'signed' their lenses in this fashion. I have read that Darlot lenses have some kind of signature, but all I have is a Darlot copy sold by Morley, which has no obvious sign of a signature. This seems to me more than just a copyright issue and it is just like a signature on a photograph or a painting to say 'this is my work'. I cannot avoid getting the image of a craftsman, in a dark workshop in the 1860s, writing or scratching this on a freshly made lens, using a magnifying glass to see. Comments are welcome.
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Thanks Michael. Mr Grubb Sr had spats with a number of parties, including Thomas Sutton who described himself as 'The Wrangler from Cambridge' (Wrangler being the term used for one who had excelled at maths in Cambridge). It became a bit of an Anglo-Irish spat for a while with the Wrangler making disparaging comments about things from the 'green isle'. Sutton went on to design one of the first wide angle panoramic lenses and was also involved with James Clerk Maxwell in the making of what may have been the first photograph in colour in 1861. It appears that egos as well as science were prevalent in the development of photographic technology in the mid 19th Century. Can you direct me to where I might find the PhotoHistorian? Thanks, William
My friend Paul Kay has had difficulty uploading a splendid photo of the inscription on Grubb Patent Doublet No 2215. It is much better than my poor effort for No 582. So, I am doing this on his behalf. Remember what Paul said about some of these letters being 0.6mm tall and think of the lighting in a workshop in the 1860s or 70s.
The next RPS Historical Group The PhotoHistorian contains a short piece on Thomas Slater, optician, and for a short time a manufacturer of photographic lenses. It contains a reference to a spat he had with Grubb, over his patent. Nothing directly relevant to William's blog post but it may be of interest.
Thanks Paul. My smallest Grubb lens, an Ax with serial number 3631 has the following engraving 'Grubb Patent No 3631 Ax'. I suspect that the last 'x' is even smaller than 0.6mm. I mentioned the French Darlot lenses in my original post. According to the earlyphotography.co.uk website some Darlot lenses have the elements signed 'Darlot Paris 10' - see the section on Early Lenses, Single Achromat Lenses. I have also seen reports of some variations of such inscriptions for Darlot lenses with similar, but slightly different engravings. Darlot and Jamin Darlot lenses should be somewhat more common than the Grubb items. Some of the single achromat Darlots have a similar pillbox design to the Grubbs, but they also have a wheel and ratchet mechanism similar to Petzvals. This, however, led to the stop always being at the same distance from the elements. Mr Grubb used a push/pull top to vary that distance as he felt that this was more useful, particularly when focus itself was being achieved using a sliding box or bellows. Some may have noted the helicoid on the lens at the back left of my Grubb group photo. This is one of the earliest examples of this feature of lens design which did not really come into common use until the early 20th Century.
I have examined other lenses from Burr, Wray, and others without finding any such trace. However Sir Howard, Thomas Grubb's son, certainly signed telescope lenses in the same way. The writing is extremely fine on Grubb lenses though and I've measured some of the letters as being about 0.6mm tall. I will forward you the example from one of Thomas Grubb's 'Rapid Rectilinear' (Doublet) lenses dating from before Dallmeyer had patented ithis design and confirming that Thomas Grubb was in fact the originator of this lens.
Thanks Wilson. It is good to see a friendly face from the Leica Forum on here. The writing of the prayer on the grain of rice must have been considerably smaller than Mr Grubb's inscription. The Grubbs came from a Quaker background, but Thomas Grubb married outside the faith and thereafter the family seemed to have regarded themselves as Church of Ireland. Certainly in the 1901 and 1911 Census returns, Sir Howard Grubb ( as he then was) described himself as Church of Ireland. I have visited the graves in Dublin of Thomas ( in Mt Jerome Cemetery) and Howard (in Deansgrange Cemetery) and photographed some of their lenses beside their graves. This might seem crass, but I believe that creators should be remembered for their works. I have also photographed those lenses beside the Grubb telescope in Dunsink Observatory and also the Grubb coelostat that was used to prove Einstein's Theory of Relativity.
Going back to the original theme of this blog, I enclose below an advertisement for Mr Grubb's lenses which makes reference to the inscription with numbering on the concave side of the lens. This would have been done after around 1864 when Thomas Grubb, who describes himself as 'Patentee' here, moved to 141 Leinster Road. I have to thank Michael Pritchard for drawing the attention of Paul Kay to these advertisements. I brought Paul to see the house at 141 Leinster Road last year. We could not go in, of course, and the house is no longer in the hands of the Grubb family. Most of the houses lived in by the Grubb family still survive, but the factory in Observatory Lane Rathmines and the original workshop near Charlemont Bridge where the lenses were made are no longer there, but plaques mark those spots. I think I have another advertisement which makes reference to the inscription and I will post it when I can lay my hands on it. If the inscription was intended as proof of authenticity, it was certainly made most difficult to find as even with a magnifying glass the inscriptions are almost impossible to see unless you know what you are looking. Even then, it is necessary to hold the concave side of the lens at various angles to get a slight glint of the inscription.
A friend of my parents had gone to the World's Fair at Chicago in 1933. He had visited the Ripley's Believe it or Not exhibit, where he had watched someone write the Lord's prayer on a grain of rice, which he purchased. This came in a small glass container where the lid was a magnifying glass so you could read how well it was written. He gave this to me but sadly it was yet another thing which vanished when my parent's moved house in the early 1970's along with a number of my father's cameras. Like for the Grubb lenses, the inscriber must have needed a very steady hand.
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