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The “Marvel” geometric compass

The Bennett “Marvel” Geometric compass is a classic example of the torturous development and ultimate failure of an overcomplicated solution to a problem that never really existed in the first place. Like so many instruments of its kind, it was the brainchild of a self-confessed inventor, assisted by a practical workman who presumably contributed the necessary technical skills.

The inventor was James Frederick Bennett, described in the 1881 census – just four years before the genesis of the compass – as a seventeen-year-old silver engraver. Bennett’s partner was one Benjamin Batty Smith, a joiners’ tool maker three years his senior. Both were just starting out in their occupations and still lived in their respective family homes with their parents and siblings in Sheffield, the centre of the British steel industry.

For whatever reason, London remained preeminent in the manufacture of drawing instruments despite a heavy reliance on Sheffield’s high quality steel. With the exception of Chadburn Brothers who were primarily makers of optical equipment and James Chesterman who pioneered steel rules, it is difficult to think of a single Sheffield firm involved in this branch of trade. Even so, Sheffield’s cutlery and toolmaking heritage offered all the relevant skills for instrument making, in close proximity to a ready supply of the finest materials, so the idea of a Sheffield-made compass is as enticing as it is unlikely.

It is unclear what prompted the two young men to collaborate on the development of what promised to be a radical reimagining of the drawing compass – reflected in its name, the “Marvel” – with the ability to draw not only circles but also ellipses and shapes of any kind and proportion. Perhaps the most credible explanation can be found in a review entitled “A New Drawing Instrument for Engineers” which begins:

“Engineering draughtsmen requiring to draw a number of hexagon headed bolts and nuts, ornamental elliptical perforations in ironwork, and other well-known and generally disliked details which in finishing drawings usually take up a share of time wholly disproportioned to the effect produced, will find friends in a couple of new drawing instruments made by Messrs. J. F. Bennett and Co., of Sheffield, and now exhibited in the Western Gallery of the South Kensington Museum.”

These were certainly the sort of technical drawing tasks that might have been encountered in the workshops of Sheffield, and that the average tradesperson would have found an unwelcome chore. Bennett and Smith’s solution was essentially a modification of Taguel’s elliptical compass which had been available in France since at least 1878, as well as being distributed in Britain by JH Steward. This, in turn, was a development of an even earlier concept patented by Alfred Joseph Hale in 1862.

That the inventors had prior knowledge of one or both of these progenitors is alluded to in their patents, which by 1885 they had begun to lodge under their joint names (“We are aware that a non-rotating foot and leg, the latter provided with a templet, are not broadly new in compasses”). This resulted in British Patent 9876 and US Patent 349203, the latter of which is the best description I have found online for the earliest known version of the compass. The accompanying patent drawings show what appears to be a prototype design, along with a second instrument intended for the drawing of volutes. The elliptical compass is striking in its physical resemblance to Taguel’s device and shares some of its key features, namely a fixed leg carrying an elliptical template and anchored to the drawing surface by needle points, around which the compass head rotates on a pivot, the other drawing leg bearing directly upon this template with the assistance of a spring.

Bennett's Marvel compass (top) compared with Taguel's patent elliptical compass (bottom) with centimetre scale
Above Bennett’s “Marvel” geometric compass, below Taguel’s elliptical compass.

However, where Taguel’s compass employed a three-dimensional template of variable horizontal section from elliptical at the top to circular at the bottom, the Bennett compass took a different approach and used a single flat ellipse cut from steel. To enable a similar range of projections, the drawing leg was provided with a secondary branch which was brought to bear directly upon the perimeter of the template. By increasing their separation via a graduated wing, it was possible to change the proportions of the resulting drawn shape.

Bennett’s design also dispensed with the sliding pen/pencil fixture devised by Taguel and which used gravity to keep the point in contact with the surface with the tendency to produce very faint pencil lines in particular. The “Marvel” instead employed a special ball joint at the base of the fixed leg (bottom right, below), prevented from rotating by an enclosed metal rod while remaining free to pivot in all directions. As a result, the compass used standard inserts which could be applied to the drawing surface with the usual degree of pressure.

Bennett's Marvel Patent Geometric Compass

Of the three physical examples of the Bennett compass known to me, only one resembles the patent design with its secondary fixing arc just below the head (this was in a boxed set listed on ebay in 2017), although even this one lacked the adjacent and somewhat clumsy-looking external curved spring of the patent drawings. A second example in the collection of the Science Museum, London, is fabricated in brass and may be an even earlier iteration. Whereas the ebay version has typically French-style pen and pencil fittings, the inserts of the Science Museum version look suspiciously like Harling’s patent “cone fitting” design. This brass model also has a threaded attachment for the fixed leg, which I assume was superseded by the rod and locking nut arrangement of the ebay set. Furthermore, the fixed leg of the brass version is tubular rather than triangular in section, different again to the patent drawing which shows an octagonal leg with a non-sliding elliptical template. Both cases feature the same gold cartouche inside the lid, which reads “J. F. BENNETT & Co. PATENTEES SHEFFIELD”.

Also in the collection of the Science Museum is an advertising pamphlet issued by JF Bennett & Co. and dated by hand to March 28, 1887. This contains an illustration of a compass that very closely resembles the ebay version. The promotional blurb emphasises the simplicity and versatility of the compass – “an ordinary school-boy can understand and use it” – but there are already signs of trouble for the business. The location of “Ellipses Works” at 35 Cemetery Road has been overprinted with a new address of Wright’s Hill, London Road. At the same time, the price of the compasses (now available in two models) have been raised by 20%, the No. 1 model now an eye-watering 60 shillings, or three pounds, far beyond the means of the “ordinary school-boy” (for comparison, this was 11 shillings more than Stanley’s top-of-the-range tubular turnabout compasses in their contemporary 1888 catalogue, or the same price as a 6-inch circular Vernier protractor in electrum).

An entry in the London Gazette of the previous October reveals the probable reason for the upheaval:

NOTICE is hereby given, that the Partnership heretofore subsisting between the undersigned, James Frederick Bennett and Benjamin Batty Smith, trading together as Mathematical Instrument Makers, at Sheffield, in the county of York, has this day been dissolved by mutual consent. All debts owing to or by the said firm will be received and paid respectively by the said James Frederick Bennett.–Dated this 27th day of October, 1886.
James Fredk. Bennett.
Benj. B. Smith.

What led to the split is not known, but it was the first in a series of dissolved partnerships for the entrepreneurial Bennett who subsequently retained control of the business. Now a sole agent, Bennett must have embarked on an publicity drive in both England and North America, as from late 1887 there was a flurry of articles and reviews in a number of engineering-related journals. These seem mostly to have been based on Bennett’s own advertising pamphlets or secondary published sources, rather than on first-hand experience of the compass. A typical example, printed in The American Machinist of October 22, 1887 gushes:

“A new mathematical instrument has been brought out by J.F. Bennett & Co., of Sheffield. It is called the “Marvel,” and from the description given in the Ironmonger the work which can be done with it is something of a marvel.”

A more useful account can be found in The Practical Engineer of February 10, 1888, which also includes illustrations of two versions of the compass, both seemingly developments of the 1887 pamphlet model. One is the familiar design, except for the omission of the upper fixing arc and a more English style of pen insert, while the other is a drop bow model with prominent external spring (looking suspiciously like Hale’s). The latter was said to be capable of drawing the same variety of shapes, but the template was formed by the leg itself, which could be unscrewed and replaced with another of a different profile.

The last of these articles I have found is dated April 1888, appearing in The Journal of Gas Lighting, Water Supply & Sanitary Improvement, which perhaps suggests that Bennett was by this time scraping the bottom of the barrel. In the same month Bennett’s name appears attached to another British patent, this time for “compass-like instruments for drawing volutes”, with co-patentees WG Mann and L Spencer. Although this indicates that Bennett had moved on from his partnership with Benjamin Batty Smith, it seems to be little more than a reworking of the volute compass included in the 1886 US patent of which Smith was co-patentee. I have found no published sources that suggest that Bennett’s volute compass was ever brought to market, nor that the “Marvel” continued to be sold post-1888.

This brings us to my recently-acquired specimen of the compass, which is essentially the 1888 model without the upper arc. It has the same triangular leg as the ebay version, graduated on two sides with different non-linear scales (see bottom right image below). The main setting wing is also divided with an numbered linear scale running from 0 to 6 in eighths (see above). Even the perimeter of the fixed foot socket is numbered 1-4, each unit divided into fifths, the purpose of which I am yet unable to determine.

Bennett's Marvel Patent Geometric Compass

The removable ellipse template that fortunately remained on the compass is interesting for its choice of proportions. As can be seen when compared with a modern Linex ellipse template, Bennett and Smith chose an almost perfect isometric ellipse (35 degrees 16 minutes), understandable given the likely audience of engineers and architects. This is important, as while extending the inner leg of the compass allows a range of other pseudo-ellipses to be drawn, tending towards the circular, the shape of the template represents the narrowest ellipse able to be delineated by the instrument. In this respect it is similar to Taguel’s design with its minimum projection of about 30 degrees, a limitation common to elliptical compasses.

Elliptical 'templet' from Bennett Marvel compass compared with modern Linex isometric ellipse template

Looking at the instrument’s style, the pencil insert is clearly of the English pattern just like the Practical Engineer illustration. It is marked with the assembly number “11” which matches similar marks on the main compass leg and inside the head. Previously I had assumed the “Marvel” compass were most likely made for JF Bennett & Co in France due to the characteristic handle design and the continental style of insert, but the workmanship of my example is strongly suggestive of an English maker despite retaining the bulbous French-style grip with its narrow vertically-knurled band. In addition, the ebay example appears to be have a nickel-plated finish, whereas mine is the more typically English solid electrum (aka German silver).

Bennett's Marvel Patent Geometric Compass

The assembly numbers in particular I find reminiscent of Harling’s work; taken together with the cone fitting type inserts of the brass Science Museum example, I am leaning increasingly towards WH Harling as a possible manufacturer. It still seems unlikely to me that the “Ellipses Works” at 35 Cemetery Road was the actual place of fabrication, although it is possible that pre-1886 models were made by Benjamin Batty Smith himself, which could explain the change in detail of my later example. The figure below is a first attempt at a chronology of the instrument’s development.

Chronology of Bennett's Marvel Patent Geometric Compass designs

In terms of the performance of the “Marvel” compass, I can now begin to understand why it was not the success its publicity suggested it would be. Even in comparison to Taguel’s similar design, I found it difficult to adjust and even trickier to draw with, largely due to the requirement of constantly adjusting the tilt of the ball-jointed foot. Although my example lacks the additional hexagonal template, I can only imagine that this would have been more difficult still to negotiate successfully. Add to this its exorbitantly high price point, and the real marvel seems to be that it survived as long as it did.

James Frederick Bennett soon abandoned the drawing instrument business, instead entering the lucrative new field of electrical engineering. The 1891 and 1901 census returns have him down as “Electrical Inventor” and “Electrical Engineer” respectively, and by 1911 he has moved on again to the emerging automobile industry as “Motor Car Business Master”. His later patents included inventions as diverse as horse shoes, radiators, gas and oil engines, a new type of cardboard, improved plastics, carburettors, buffers, tape measures, tennis court markings and even a modified curling stone fitted with ball bearings to allow the game to be played on a linoleum floor or billiard table. In all, his name appears on about fifty patents between 1894 and 1935.

Benjamin Batty Smith, meanwhile, continued in his previous line of work as a maker of joiners’ tools up to and including the 1901 census. He died just three years later at the age of 44, a depressingly common outcome for Sheffield’s working toolmakers. Unlike many thousands of his equally unfortunate colleagues, his name is at least remembered by the compass he helped to create, a beautiful but flawed example of the instrument maker’s art.

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