Miscellaneous surveying

Box sextant by W F Stanley in oxidised brass with silver scale and vernier, probably early 20th century, in excellent working order

Heath Hezzanith Rapid Reader Survey Sextant made by W F Stanley at New Eltham (Stanley took over Heath in 1926). The NPL certificate is dated 1954 (when it was new) and the W F Stanley one is dated 1983. The black cylindrical tin holds the spare mirrors. The four filters fit over the telescope eyepiece. The small brass item with knurled handle is for locking the fine adjustment of the horizon mirror I think.

Adjustable Cross Staff by “La Filotecnica” Ing A Salmoiraghi, Milano. Early/mid 20th century. There is a compass in the top.

The surveyor’s cross was another instrument used for laying off offsets at right angles. In this case sightings are taken through the narrow slits and via the fine line opposite. This particular instrument has a compass in the top ( for which there is a brass cover, not shown) and is octagonal in section suggesting that it was made in France (English ones were more likely to be round and of larger cross section). The letter “O” for “Ouest” confirms it as French. It has a socket underneath for mounting on a staff. It has a mahogany box.

A brass optical square by an unknown maker. It has a leather case with a belt loop, probably dating from the 1930s. It may have been black finished originally.

These optical squares were constructed like the apomecometer above but with the mirrors at an angle of 45 degrees to each other rather than 22.5 degrees. There was also a double version of the mirror type, to sight at 90 degrees left and right simultaneously.

Used to ensure offsets were measured at right angles when chaining.

E R Watts & Son Ltd, London double optical square no. 33179. Dating from ca.1943, this is the prismatic type, in this case with two prisms, one above the other, to sight at 90 degrees left and right simultaneously.

It has a black, cloth covered, card case.

Used to ensure offsets were measured at right angles when chaining.

J Halden & Co optical square of the mirror type. It has a fitted, round, leather covered and blue velvet lined case. Probably ca.1900.

MDS Ltd “improved” optical square no.1534. Mid 20th century. At 2¾” diameter it is larger and heavier than the other optical squares in my collection. There is a bubble level inside the right angle aperture that can be seen with the reflected object. The mirrors are in poor condition. MDS were founded in 1920 as the Miscellaneous Disposals Syndicate Ltd, dealing in government surplus items. Ca. 1940 they were renamed the Manufacturers & Distributors Syndicate Ltd. Their address was 41 St James Gardens, Holland Park, London W11 and they had a factory at Empire Works, London Road, Horley.

Double optical square dating from ca.1960. This is the prismatic type, in this case with two prisms, one above the other, to sight at 90 degrees left and right simultaneously. Made in England, same as the Stanley A1531. Leather zip fastening case and cord for hanging round the neck.

Site Square marked Made in England. It has a black leather sling case. Used for laying out right angles on building sites, etc. Probably made by Rank Precision/Hilger & Watts

Plane table and stand. The plane table measures 24” x 18” and is to the Royal Engineer’s pattern. The underside shows the aluminium corners, battens and race. The carrying bag is canvas with leather corners. Mid-20th century.

12” boxwood and brass folding alidade by J H Steward Ltd, 457 Strand, London. Originally the property of Bedford College, London, Geographical Department, the stamp of which is impressed in both the alidade and its leather case.

The edge scales are yards 6” to the mile and 2” to the mile.

It probably dates from the first quarter of the 20th century.

W Ottway & Co Rules Sighting 24” No A339 1924. This combined alidade and parallel rule was intended for use on a plane table by an army surveyor. The adjusting key shown right is housed in the small pocket on the face of the case. The rule is made of aluminium. The wooden case is lined with green felt.

Lufkin Rule Co, Saginaw, Michigan, USA 100ft steel surveying tape, mid-20th century, in a steel frame with hardwood (rosewood?) Handle. The “Nubian” finish tape is 3/8in wide and 0.015in thick.

The L S Starrett Co Athol Mass. USA 50ft/15m metal tape measure in a leather case. No 5108. Imperial measures one side,metric on the other.

John Rabone & Sons, Birmingham, England no.4351 100ft steel surveyor’s tape in a metal case, early to mid-20th century.

I have other surveying tapes that are cloth and leather cased by Rabone, by Chesterman and by Dean Bedington.

66 feet land chain (Gunter chain) consisting of 100 links, each tenth identified by a brass tag. This is a very basic chain made of 9 WG iron wire except for the brass handles and tags. The handles simply swivel on the wire and there are three other wire swivels at 25, 50 and 75 links respectively to prevent kinking. There is no indication of the maker. Simple iron chains were significantly cheaper than those made of hardened and tempered steel wire.

Reid & Young, Glasgow anemometer or airflow meter used to measure the airflow in mines, corridors, chimneys and ducts of all sorts. On the right is a ducted fan that is placed across the direction of flow. On the left edge of the instrument a lever is used to start and stop the counting mechanism by engaging or disengaging it from the fan. It is first zeroed using three keys that are accessed through holes in the base plate. It is the started and timed for one minute at which point it is stopped again. The velocity can then be read directly in feet per minute. Serial no. 11161. Reid & Young were in business from 1913 to 1964.