Late Victorian Cased Hypsometer by Cary of London

For sale, a Late Victorian Cased Hypsometer by Cary of London.

Contained in a leather carry case, this compact travel hypsometer is comprised of a spirit burner, a water vessel with telescopic jacketed column, two varying scale thermometers and an outer black painted, two part canister in order to allow steam to circulate. All of the components are neatly arranged so that they can be stored conveniently whilst travelling.

This uncommon instrument first invented by the eminent scientist William Hyde Wollaston and later improved by numerous others, is used as a means to measure elevation using atmospheric pressure. Its principle is based upon the fact that the boiling point of water becomes lower as atmospheric pressure becomes lighter. To use the instrument, water would be placed in the base of the telescopic column with the barrels extended and with the spirit burner placed below, the water would be heated to boiling point. The aperture at the top of the column allows for a thermometer to be placed inside in order to measure the boiling temperature of the water at a given elevation and through calculation, an exact elevation could be attained.

Popularised in the mid Nineteenth Century and used extensively in India for surveying by Colonel Sykes and later General Boileau (the pun is not intended), the hypsometer was considered a much easier instrument to carry for travel than attempting to manage the fragility of a mercury barometer in hard to reach and rugged terrain. This fact was not lost on the earlier manufacturers such as Casella. His catalogue of the early 1880’s states:

“Wherever the measurement of mountain heights is required to be taken by other means than the theodolite, or standard barometer, or where there may be danger or breakage of either, without any means of comparing or replacing them, this cheap and simple means of measuring heights will be found both efficient and handy, and it is at all times a reliable test with which to compare an aneroid or any other similar instrument, which from time to time requires to be compared and adjusted”

He continues to provide a quote from the famous Himalayan explorer, John Dalton Hooker:

”For the measurement of great mountain masses and continuously elevated areas, I conceive that hypsometrical results are as good as barometrical ones. For the general purposes of botanical geography, the boiling point thermometer supersedes the barometer in point of practical utility; for under every advantage the transport of a glass tube full of mercury, nearly three feet long, and cased in metal is a great drawback to the unrestrained motion of the traveller.”

The quote is insightful but perhaps moreso a masterclass in advertising. It is certain that the hypsometer was certainly an advantageous instrument over the mercury barometer but the quote by Hooker was likely to have been made in the 1850’s after his return from the Himalayas (30 years before) and more importantly, the new aneroid barometer had largely superseded the requirement for either instrument. Casella is of course, well aware of this development and gently argues the case for the hypsometer as a means to compare aneroid readings.

Having said all of the above, it does seem that the hypsometer did continue to be of some value. This example can be dated quite succinctly to the 1890’s and they continued to be produced into the early part of the Twentieth Century but their use dwindled in favour of the developments in aneroid barometers. It is another instrument much like the Adie’s sympiesometer that was developed in the Early Nineteenth Century and although considered of scientific value, only had a relatively short period of success due to the aneroid. As such, both are less familiar and certainly less common than their successor.

An interesting and complete example by a well respected London firm.