Today’s post showcases a set of six W.F. Stanley vulcanite chain scales and matching offsets, something that had been on my wish list for a long time. Vulcanite (aka ebonite) is a hard rubber material developed in the 1840s and popularised at the Great Exhibition of 1851, initially for decorative items due to its ease of moulding and attractive jet-black appearance.
Stanley is the only maker that I have seen Vulcanite scales from (for example, these unfortunate specimens in the Science Museum, London), although it was occasionally used for the large protractors found in military “Woolwich” cases by Elliott Bros and possibly others.
Oddly enough, Stanley did not approve of vulcanite for use in scales for reasons that shall become apparent, and the material is not mentioned in the 1868 edition of Mathematical Drawing Instruments, which states:
“The only materials employed for drawing scales, except boxwood and ivory, are metal and paper. Metal scales are expensive, and soil the drawings.”
However, Vulcanite does appear elsewhere in the book. In the section on set squares, Stanley enthuses:
“The author, after several experiments in seeking some suitable materials for plain set squares, has discovered that Goodyear’s vulcanite, which is a patented preparation of India rubber, of which the best qualities are manufactured in North America, possesses all the qualities desirable for set squares to be used in temperate climates. This material is considerably harder and tougher than any kind of wood; it is impervious to moisture, consequently it may be kept clean, if required, by washing, and it will not warp or get out of truth under any ordinary circumstances.”
Likewise, on the subject of curves:
“The vulcanite mentioned for set squares makes very excellent radii curves for temperate climates, but the cost of the material prohibits their general use.”
This price premium can be seen in Stanley’s 1865 catalogue, where “Stanley’s vulcanite Set square” (with the note “Recommended, very hard, keep true, and bear washing”) at one shilling was twice as expensive as the equivalent in ebony, and three times the cost of pear wood. The prices remained the same in Stanley’s 1869 price list, but by the following edition of his book in 1873 the cost objection had been dropped from the text, indicating that the price had begun to come down. Unfortunately, a new obstacle appeared in this edition, with the addition of a short sentence to the earlier list of materials suitable for scale rules:
“Vulcanite has been used a little for scales; it is affected very much in length by changes of temperature, therefore it is unfit for them.”
This would seem to be the death knell for vulcanite scales, but in spite of Stanley’s blunt assessment, they are back in the 1878 edition with a new qualification:
“It is preferred by a few, who state that it is soft to look on by night, and less trying to the eyes.”
Clearly this small band of devotees continued to demand the scales, and by the 1888 edition Stanley sounds almost conflicted on the subject:
“Vulcanite is used a little for scales. It was originally introduced by the author, but is not recommended.”
By this time Stanley had been making vulcanite scales for at least twenty years, all the while exhorting his readers not to use them. This contradiction is apparent, in that they were never included in the price lists at the back of Stanley’s book, but do appear in his catalogues (for example, the 1888 list which includes my particular set as “Chain scales, 12-inch, and offsets, set of 6, both sides alike, or in feet and links, in case. Box 21s. Ivory 63s. Vulc. 32s. Electrum 105s.”)
It was perhaps his bitter experience with vulcanite scales that led Stanley to sound uncharacteristically cautious over the introduction of celluloid, first mentioned in the 1900 edition of his book:
“The author has tried some experiments of making boxwood scales with opaque celluloid edges cemented on the wood. Some of these scales have stood by for three years, and appear to stand very true. They are very clear to read, and are worthy of trial.”
Even though the success of celluloid-edged boxwood scales (first introduced in 1886 by the German firm of Dennert & Pape) should have finally seen off vulcanite, it continued to be offered as late as the 1924 Stanley catalogue, with the same caveat:
“Any scales can be made of vulcanite, but these are not recommended, as they expand greatly with heat.”
Quite how many sets of vulcanite scales were sold over their half century of reluctant production is difficult to say. It would be a stubborn breed of architect or surveyor who ignored all the warnings and paid a 50% premium over boxwood for a set of scales that might not even be to scale. How many of these sets survived intact is yet another matter, judging from the Science Museum’s assorted shards (perhaps hurled across the drawing office by the hapless purchaser on finally seeing the folly of their ways). Regardless, they are almost certainly the coolest-looking scales in my collection.