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Founded in 1880 at 109 Deansgate, Manchester by Alexander George Thornton, the firm grew to become one of the largest manufacturers of drawing instruments and slide rules in Britain. The Precision Instrument Co was taken over in 1901 and PIC continued to be used by Thornton as a trade mark until about 1970. The firm became British Thornton in 1967 and merged with ESF at Burley in 1992. British Thornton is now a manufacturer of school furniture in Keighley.
A traditional pattern set of electrum instruments by A G Thornton dating from the late nineteenth century.
The instruments were purchased loose and I adapted an empty steel case to take them by making a set of velvet lined pockets to fit the instrument tray of the case in the same way as they would have originally been made.
A six inch circular protractor by Thornton of Manchester. This copper alloy protractor is probably gun metal but could be brass. About 1900.
A "British Empire" pattern set, dated 1939, made for H M Government.
This pattern of instruments was basically that “approved by the Inter-Departmental Committee appointed to consider the design of British drawing instruments” (ref: Casella  catalogue no. 564 p173). They were made with minor variations by several British manufacturers.
A "Minerva Series" set in a large 'pocket' case.  Thornton introduced the Minerva series prior to 1916 (they appear in the catalogue for that year) and continued making them until, at least, the 1950s.
The section Miscellanea (Who Made Them) features a Halden Premier set in which the metal instruments are of the Minerva series pattern. It is highly probable that Thornton made the electrum instruments for the Halden Premier sets as they were better quality than Halden’s own manufacture.
The Minerva series compasses and dividers were copies of
E O Richter’s flat system that A G Thornton had sold prior to the First World War.
A Thornton Minerva set in a tropical case. Besides the usual instruments the tray contains a drop bow compass.
The bottom of the case contains celluloid curves, a protractor and a Thornton Kinwest six-inch adjustable set square.
Another Thornton Minerva set in a tropical case. This one includes a celluloid clinograph.
Thornton Minerva insert spring bow set. The four inch spring bow can be lengthened to six inches by fitting the two extension bars. It has two each of pen, pencil lead and divider needle point inserts and there is also a pen handle. Mid-20th century.
Thornton Techset instruments in a wallet case. The Techset series were a cheaper version for students, based closely on the Minerva series.
A small case of Techset instruments. The compass and dividers are smaller size instruments.
The Jaywess series of instruments, made by Thornton, were their cheapest range, aimed at technical schools.
A small Jaywess set. The turnabout spring bow did not feature in their more expensive sets but was common in Jaywess ones.
This eight inch "Thornton PIC" adjustable set square was purchased by me as a student in 1963 and the transparent part is acrylic. It is still in use when a square is needed.
A set of British Thornton instruments dating from about 1970. It includes large and small spring bows, a beam compass, dividers and a drop bow (or rotating) compass. The instruments are housed in plastic foam (which has been replaced as the original had perished to dust) instead of velvet lined pockets. The instruments would probably have been selected and then the appropriate size case purchased to house them.
VC7983 Compasses, Beam, 26” T.P. (Thornton Pattern) B8025. Roller beam compass, presumably by A G Thornton, patent number 155970/19. A set of beam compass fittings made for the WD in the mid twentieth century. Brass and steel. One of the long steel points would be clamped to one end of the beam by the smaller fitting (top left). The larger fitting (top right) has a spring at one end and a roller at the other. The insert holder (bottom right) fits into this fitting and either the pen, pencil or needle point insert can be fitted in this.
This type of beam compass (but nickel silver) is shown in the 1930 B J Hall catalogue where it is described as “Gill’s Patent no. 155970/19”.
Thornton Minerva beam compass. This is the same type of beam compass as the one above but has a plated finish and a two section, rectangular Aluminium tube, beam that is 18.5” long when assembled. It probably dates from the 1950s. The case is lined with black silk & velvet.
Set of electrum and steel spring bows, probably Edwardian. Unusually they have hexagonal handles and centre thumb wheels. The pen & pencil bows are fitted with Thornton’s Improved Nut & Bolt points (Rd. No. 354,874), whilst the divider bow has plain points. Morocco covered, blue silk & velvet lined case.
Ministry of Works set no. 5136 made by A G Thornton in the mid-20th century. The instruments are based on the Techset series but appear to be made of a light coloured brass rather than electrum. The pen handles are ivorine, as is the Protractor Rectangular 6 inch Ivorine A Mk IV. The parallel rule is boxwood. This set is of a type made by several manufacturers to what appears to be a government specification.
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British Empire pattern set made for the British government in 1938. Oddly, not all the instruments are signed Thornton. The large compass, dividers, bow compasses and parallel rule are marked Harling and the protractor is by GH Cooper and dated 1936. The pens are unsigned. There could be a number of reasons for this. This set is higher quality than the MOW set above.
B J Hall Simplex set of drawing instruments dating from the 1930s and catalogued by B J Hall as D 321. It was in fact made by A G Thornton and is identical to their Minerva set  E9511 / F9511. The larger ruling pen has been broken and the handle shortened at some time. The beam compass fittings are Gill’s patent.
Thornton traditional pattern full set in a Morocco case. It is missing one ruling pen and one spring bow is incorrect.
Another traditional pattern set by Thornton; this one is in a polished wood, pin-lock case and higher quality than the one above. The two smaller ruling pens are replacements, as is the agate pointed tracer. It is missing a fine line pen, pricker and compass extension bar. Thornton was at St Mary St, Deansgate, Manchester from 1897-1904.
A set of Swiss pattern beam compass fittings signed A G Thornton 109 Deansgate, Manchester. The points are the patent screw-off type.
A Thornton Minerva six inch spring bow or master bow compass dating from the 1950s probably
Thornton Minerva detail pen MS81 again probably dating from the 1950s
A complete set of twenty lancewood splines by A G Thornton. These were used with special weights to draw long curves, particularly by ship designers and naval architects. Many of the splines are tapered so that the curve would vary in radius along its length as the spline thickness, and hence its stiffness varied. There are five 5 foot, five 4 foot, six 3 foot and four 2 foot splines in this set. I’m now looking for the weights that would have been sold separately.
Like the set of Thornton spring bows in an earlier picture, these have hexagonal handles but these have side adjusting wheels and have ordinary nut and bolt needle points. Morocco covered, blue silk and velvet lined case. One electrum handle has ‘patent’ on it and the other two are stamped ‘Thornton’
Ca. 1960 Thornton Minerva set of electrum & stainless steel instruments. The pens have plastic handles. The compass and divider have ball bearing, self-centring head joints for which Thornton obtained a patent (GB684,850) in 1952 (applied for in 1950). The pricker is an original addition to the set, which is in pristine condition.
Pencil compass made by Thornton for the UK government marked with the broad arrow and 13/94 (both compass and case marked) and dated 1956. The set, to a government specification, comprised the compass and separate containers for leads and needles. The head is the ball bearing type but not self-centring. I believe these compasses were originally intended for aircraft navigation and were made by a number of makers, especially in WWII. I have a 1942 example by Aston & Mander. Each maker had their own design.
A 1940 Thornton pencil compass and wood box, both dated 1940 with the Air Ministry logo. This compass has the “Techset” type of head. Another of these Air Ministry compasses in my collection was made by WEDOCO in 1942.
Set of six 10”, single sided, scales by A G Thornton numbered 2 to 7 (there was probably a number 1 as well originally) in a leather case. Scales 2 to 5 are unusual as they have a centre zero one edge and a zero inset by the finely divided first and last increments on the other (open divided) side, which is tleft and right reading. They are for 3/8, 1/2, 3/4, and inch. Scale 6 is inches x 50ths and scale 7 is cms. Thornton offered a very wide range of scales with several different forms of dividing and would also divide scales specially to customer’s requirements.
A 14” polished oak case of traditional English pattern drawing instruments by A G Thornton, 109 Deansgate, Manchester dating from ca.1890 The spring bows and six-inch compass have screw-off points and the latter was made by W H Harling as possibly were the spring bows. At this date Alexander George Thornton did not make all of the instruments he sold and some were certainly bought in, so I am pretty certain these were all original to the set. There is an abandoned W H Harling patent no 1027 of April 23rd 1888 that I think covered these screw off points and they are found on sets by Harling, Thornton and Halden from this period. In every case the spring bows have the same, unusual, 3 knurled rings on the handle and were undoubtedly made by the same manufacturer. The pens in the top tray are all signed Thornton and one is Thornton’s Self-Filling Drawing Pen designed by A M Low Esq, registered no. 522051. Since it was registered in 1908, about ten years after Thornton left 109 Deansgate, this must be a later addition or replacement. In the lower tray are four further pens (one signed Stanley) and a pricker with patent screw off point. It is likely that this pricker is original to the set as may be one of the other pens. Another interesting item is the drop bow compass as it is an early example of E O Richter’s patented design that Thornton imported and illustrated in his 1895 catalogue. It may well have been purchased with the set as the items in the second tray and base were optional, such as the set of water colours, mostly by Geo Rowney & Co, included in this case. This would also have applied to the ivory protractor, in this case a 5” one that is unsigned but again dates from when this set was purchased. The boxwood 6” rectangular protractor is by Rowney so could also be original or an early addition. In the base are six scale rules. Four are by Thornton but, interestingly, two have the same scales and one is an Armstrong scale, the oter three being chain scales. There is a second, unsigned Armstrong scale and an ivory scale signed J Archbutt & Sons. These muse have been added at some time after the set was first purchased although the ivory scale is probably older than the set and is in rather poor condition. There are also four un-used 4H & 5H pencils in the base - typical drafting pencils made by A W Faber. When purchased there were also a number of other instruments and parts that are now in my spares boxes.
A 1950s Thornton Techset. Whilst still basically to the same design as the pre-war version with which the inserts are still interchangeable, there is one important difference. The head design of the compass and divider has been changed and now incorporates a hidden centring device. Note also that the C springs and pivots of the spring bows are now brilliantly blued steel. Since the set was given to me I have cosmetically restored the case using matt black enamel paint on the bare patches, followed up when thoroughly dry by polishing with black shoe polish.