20th century Ahrend 20m chain nr. 7401

The 20th c. Ahrend chain nr. 7401.
Figure 1: The 20th c. Ahrend chain nr. 7401.
This chain appeared on a Dutch on-line auction site in October 2018. Although I had already quite a few chains in my collection, the one shown here was of interest as it was 20 metres long, made of 40 half metre links. This makes it double the size of the 19th c. Lerebours chain in the collection and about the length of the imperial 19th c. Doyle and Son Chain.

The chain was retailed by the Ahrend, who also retailed the steel tapes model 7421 and model 7427.

The links are connected with each other using rings of the same material of the links themselves. Every second ring a triangular label indicates the length along the chain. At 10 metres a barrel shaped connector is used. This connector allows rotations along the chain, but also adjusting the length of it as it is fastened to the links with threaded eyes. This type of adjustment was however not very practical as the screws would get clogged with rust and sand,1 and it was therefore recommended to either adjust or to keep track of its true length.2


The Ahrend chain compared to the 10m Lerebours chain.
Figure 2: The Ahrend chain compared to the 10m Lerebours chain.
Chains of this type, so containing 40 links of half a metre each, have already been described in the nineteenth century by Brandenburg,2 but this particular example most likely dates from the 20th century as the firm Ahrend was established in 1896.

In general the handles of chains and steel tapes have grooves, sometimes both pointing towards the chain, sometimes pointing in opposite directions. These grooves were to place the handle correctly against the 6 or 11 skewers that were used to stake out or measure a length. When pointing in opposite directions one is not dependent on the thickness of the skewers.3 This Ahrend chain has them both pointing towards the chain for which one had to use skewers of the correct thickness.

Although the handles are identical in shape, one is punched with the indication "0m", the other with "20m" (see figure 5). Both handles bear the text "AHREND NO. 7401" and the text "NIET VOOR HANDELSDOELEINDEN", the latter indicating that the chain should not be used for trading purposes (i.e. for taking measurements of products that are sold by length).

Notes

[1]: G.A. van Kerkwijk, Geodesie voor de Kadetten van alle Wapenen: Wiskundige Leer-cursus ten gebruike Der Koninklijke Militaire Akademie, (Breda, 1842), p.7.
[2]: P.J. Brandenburg, Beginselen der Werkdadige Meetkunst: voornamelijk voor de aanstaande officieren der infanterie bij het Nederlandsch-Indische Leger, ('s Gravenhage, 1888), paragraph 36.
[3]: Ch.M. Schols, A.C.C.G. van Hemert, Landmeten en Waterpassen: Met een Atlas van 19 Platen, (Breda, 1899), p.102.

If you have any questions and/or remarks please let me know.

The whole metre ends of the links with their tags.
Figure 3: The whole metre ends of the links with their tags.
 
When folded the other ends of the links have no tags.
Figure 4: When folded the other ends of the links have no tags.

The handles of the chain have the hollows for the skewers on the same side.
Figure 5: The handles of the chain have the hollows for the skewers on the same side.
 
Despite being equipped with nuts on the handles and 5m markers, the chain cannot be adjusted.
Figure 6: Despite being equipped with nuts on the handles and 5m markers, the chain cannot be adjusted.

Surveyor's crosses Geodetic Sextants Theodolites Total Stations Levels Standards Tools Firms
1953 Wild K2 Alidade 19th c. measuring rod 19th c. Lerebours chain 20th c. Ahrend chain 20th c. Chesterman chain 20th c. Tibaut steel tape 20th c. Ahrend steel tape 20th c. Ahrend steel tape 1980s DOSbouw clinometer