Accession No

5790


Brief Description

evaporimeter, The Air Tester “Dragoyle”, with its box and instruction booklet, by John Swain and Son Ltd., English, early 20th Century


Origin

England; EC4; London; 89-92 Shoe Lane


Maker

John Swain and Son Ltd.


Class

meteorology


Earliest Date

Jan. 1, 1900


Latest Date

Dec. 31, 1950


Inscription Date


Material

paper (card, cardboard); plastic (bakelite); glass; cloth (cotton, muslin); metal (lead, alloy); liquids; thread (cotton)


Dimensions

dragoyle height 85mm; diamter of base 88mm; height of box 78mm; depth 95mm


Special Collection


Provenance

Purchased from Christie’s South Kensington, 85 Old Brompton Road, London, SW7 3LD on 1/6/2000. Lot 161 in sale MSI-8778.


Inscription

on the box lid
THE AIR TESTER
(British Patent No. 230617/24)
A SCIENTIFIC INSTRUMENT
IN A FASCINATING FORM
used in conjunction
with a Thermometer
will correctly indicate how the best
working air conditions in Factories,
Offices, Rooms, etc. may be obtained
Sole Agents for the United Kingdom of
Great Britain, Ireland & Isle of Man:
JOHN SWAIN & SON, LIMITED,
89-92 Shoe Lane, London, E.C.4.


Description Notes

The Air Tester “Dragoyle”, early 20th Century by John Swain & Son ltd.

Evaporimeter, partly concealed within a model ‘Dragoyle’

A circular bakelite base on top of which is glued the “Dragoyle's” body, a green painted lead sea lion type figure. The head is linen dyed green covering the glass air testing apparatus. The linen is shaped to resemble a sea lion head and from its mouth projects the glass tube of the air tester apparatus, this has an “S” bend at its end. Inside the glass bulb and tube is a red coloured liquid. The head is placed on to the body and its neck of linen and muslin goes into the body.

The box lid (outside) has a paper label attached describing the product. Attached to the inside of the lid is a set of instructions on green paper. There is also a small stapled booklet on its use and the “Science” behind the air tester. [Scan of Dragoyle instruction booklet and images of outside and inside of box lid are in ‘Research’ folder on Bertrum]

The air tester measures the rate of evaporation of water in the air.


References

Allison Ksiazkiewicz; 'Measuring Air Humidity'; Explore Whipple Collections online article; Whipple Museum of the History of Science; University of Cambridge: https://www.whipplemuseum.cam.ac.uk/explore-whipple-collections/meteorology/measuring-air-humidity


Events

Description
This instrument is an evaporimeter, which measured the rate of water evaporation, enclosed in a ‘Dragoyle’, a cross between a dragon and a gargoyle. The faster water evaporated from the hidden reservoir, the faster the Dragoyle’s head bobbed back and forth. This was meant to indicate whether the room’s heating or air flow needed to be adjusted to reach ‘correct air comfort’. It was designed to be used in factories or offices.

[Label from Measuring Air Before Covid display]
26/09/2022
Created by: Morgan Bell on 26/09/2022


Description
The evaporimeter in enclosed within a fanciful creature, the ‘Dragoyle’. The tube leads into the reservoir hidden within its body.

The evaporimeter was designed to test “air quality” by recording how quickly water evaporated from the reservoir inside the Dragoyle. The faster water evaporated, the more rapidly the Dragoyle’s head bobbed back and forwards.

A simple evaporimeter of this type was described by American scientists working in the Panama Canal Zone in the 1920s. The principle was incorporated into the ornamental design and manufactured as the ‘Dragoyle’ in the USA, being soon copied in Britain.


FM:46192

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