A COLLECTION OF MORSE TELEGRAPH AND RADIO RELATED ITEMS FROM THE RADIO STATION OF M6BRN.

#15959

#212136

Abney Levels and Clinometers

Abney level and clinometer by J.H. Steward Ltd. Circ 1940.

This example of an Abney level and clinometer was manufactured by J. H. Steward Ltd from the registered address of 406 The Strand, London and was manufactured around 1940. It is complete with its leather carry case and is in very good condition. The company of J. H. Steward Ltd was established in 1852 and finally closed its doors in 1975.
An Abney level and clinometer is an instrument used in surveying which consists of a fixed sighting tube, a movable spirit level that is connected to a pointing arm, and a protractor scale. An internal mirror allows the user to see the bubble in the level while sighting a distant target. It can be used as a hand-held instrument or mounted on a Jacob's staff for more precise measurement, and it is small enough to carry in a coat pocket.
The Abney level is an easy to use, relatively inexpensive, and, when used correctly, an accurate surveying tool. Abney levels typically include scales graduated in measure degrees of arc, percent grade, and in topographic Abney levels, grade in feet per surveyor's chain, and chainage correction. The latter is the cosine of the angle, used to convert distances measured along the slope to horizontal distances. By using trigonometry the user of an Abney level can determine height, volume, and grade.
Abney levels are made with square tubular bodies so that they may also be used to directly measure the slopes of plane surfaces by simply placing the body of the level on the surface, adjusting the level, and then reading the angle off of the scale.
Abney level and clinometer by Francis Barker & Sons (1932) Ltd. Circ 1940.

This example of an Abney level and clinometer was manufactured by Francis Barker & Sons (1932) Ltd and was manufactured around 1940. On this model the sighting tube is telescopic allowing you to sight the target at a longer focal length and be able to rotate the spirit level with a micrometer adjuster at the side of the protractor. The company of Francis Barker & Son was established in 1848 and was a prolific compass maker. Francis also put his name to many instruments that he sold but didn’t manufacture like telescopes, binoculars and levels but obviously they would have been of such quality that he was happy for them to bear his name. After Francis’ death in 1880 the company was run by his sons, nephews and grandsons but they lacked Francis’ acumen and by 1932 Barkers was in serious financial trouble where it was taken over and renamed Francis Barker & Son (1932) Ltd. This company did well and benefited from the Second World War. Although it changed hands several times over the decades, it still survives today and is owned by Pyser-SGI Ltd who continues to produce world class compasses bearing the Francis Barker name.