View Full Version : Dating Horne, Thornthwaite & Wood lenses

28-Sep-2009, 11:14
I recently bought an early Petzval lens engraved Horne & Thornthwaite, 123 Newgate Street with the serial number 1345.

Horne & Thornthwaite operated from Newgate Street from 1854 onwards, before that date they were operating from that address as Horne, Thornthwaite & Wood.

I disassembled the lens to clean the elements and discovered a pencilled inscription around one of the rear pair of elements saying "Horne, Thornthwaite and Wood"

It seems to me likely that this lens was produced at just about the period that Wood left the partnership. The optics were assembled while Wood was still there, but the lens barrel seems to have been engraved after his departure, presumably later in 1854 or early in 1855.

This is useful information as the lens Vade Mecum can only hazard a guess that several lenses with serial numbers in the 3000s date to 1858.


29-Sep-2009, 07:25
That's a rare one, good shooting to you. Good to see you over here Sean.

Steven Tribe
10-Aug-2017, 06:07
The original poster is no longer with us. He was the instigator of the scanning of the Dallmeyer ledgers which are now at the Dallmeyer archive. A fantastic source and quite unique.

Parallel with efforts with Hermagis and Lerebours dating, I thought it might be worthwhile to have a go at putting serial numbers on the various versions of this London Company who had different names and different address at known dates.
In particular, Wood was in and out of the company a number of times.

The basic information about their history can be found here - and I think it is basically very sound.

I don't know whether the serial number sequence continued unchanged through the company changes, but it would nice to find out!

Steven Tribe
12-Aug-2017, 07:34
Here is some better infomation from the first two posters made elsewhere!


and some interesting stuff - relating mostly to general optical instrument work/personal historys - here.


Steven Tribe
15-Aug-2017, 06:09
The reason why I have "reopened this case" is because I have bought a little Horne & Thornthwaite - mostly out of curiousity!

Looked like a size 1 CdeV lens, but it certainly isn't. The front lens is an achromat but the rear is a simple bi-convex lens. Both have the UK system of burnished mounting. The lenses are at Petzval-like distances.

There is a fixed baffle, but also a cup-like small internal aperture which screws onto the rear lens cell. Could this be the obscure "caloscopic" lens mentioned in Lens Vade Mecum? The structure looks similar to a Liddells of Edinburgh lens I have from the same period.

As soon as I have some more serial numbers, I'll post a table showing these alongside the company names and London addresses. The company made a lot of besoke optical instruments, as well as a novelty apparatus for showing the wonders of prime colour mixing to produce magic additives!
The design of the engraving on lenses is similar to their company identification on microscopes etc., but serial numbers appear to have reserved for photographic lenses

There is an 1856 catalogue on the web. All pages can be viewed and pages are turned by "swishing" from the top right hand corner. There are plenty of illustrations of different cameras from the mid 1850's.


I have found a single lens without a serial number.

Steven Tribe
16-Aug-2017, 03:20
In the 1856 catalogue, I did, in fact, find my mystery lens. It is a double achromat - with a distinctive thick rear achromat. I include the description below. It is an obvious design, considering what was going on elsewhere - the Ross double achromat designs and the French convertible Petzvals. Mine is obviously one the small models, made for 4x3 or 3x2.

I am a bit surprised the authors of the Lens VM didn't discover this lens, as it is mentioned as winning a prize at the London Exhibition of 1851 (Crystal Palace Exhibition) and probably predates the Ross version!