Description and Notes:
As shown in the picture above, this rare tubular compass set comes in a well made, beautifully figured rosewood veneered wood case. It also contains an ebony parallel rule which is signed W ELLIOTT & SONS 56 STRAND LONDON. The other instruments however do not bear any maker's signature (the ivory handled pricker and ruling pen are also made by Elliott but they are later substitutions, the original ones in the set are missing upon acquisition). According to the Directory of British Scientific Instrument Makers 1550-1850, William Elliott & Sons were working at 56 Strand, London from 1850-1853. Therefore this set may be dated to the beginning of the second half of the nineteenth century.
The tubular compass of this set is in its original form of construction, which was described and criticized by W. F. Stanly in his book, pp. 36-37, as:
In construction, the tubular compasses have points
as the other compasses already described. The legs are formed out of a pair of tubes, each of which encloses an inner tube or bar, fitted that it may slide out in the manner of the tubes of a telescope, when the compasses are required to be extended to produce a large circle. Upon the ends of the inner tubes or bars the points are jointed, so as to turn down in use to an erect position,
in the manner of the compass points described. Besides the turn-down joint, each point has a swivel joint, which allows either the ink or pencil, or plain point, to be turned outwards, so that one only of them may form a point to the compasses. The common defect of this kind of compasses is unsteadiness, owing to the weakness of its construction, which is caused principally by the inner tube having a slot down one side to admit of the introduction of a clamping screw to a nut within the inner tube, for holding the instrument in position.
and he proposed that:
Tubular compasses are much better if made with a solid bar instead of an inner tube. If a slot be made down the bar, and a corresponding slide fitted into it,
and connected with the outer tube, the friction of the slides will be quite sufficient to hold the point steadily. In any position, dispensing with the very objectionable clamping screw.
However his criticism does not justify on the one of this set, because it satisfies every criterion which he designated to a well made one:
Tubular compasses are very frequently badly made; in selecting one, the tubes should be pulled out as far as they will go, the compasses opened into a straight line, and the points turned down as if for producing a large circle; by taking one point in each hand and twisting the points with a rocking motion, it may be easily ascertained if the work is sound. In other points it is only necessary to observe that the joints move evenly and the tubes firmly.
As mentioned earlier, the pricker and ruling pen are acquired elsewhere as a partial set which also contains a turnabout bow compass made of brass also by Elliott. These three instruments are of later date and the initials of the original owner, R. B. P., are engraved on them. The design of the pricker is identical to the one patented by Stanly, and the cap of which can be unscrewed to revel a storage compartment for spare needles.