two thermometers for psychrometer
Date1900-1910
Inventory Number2008-1-0095a,b
ClassificationThermometer
Subject
Maker
Henry J. Green
fl. 1885 - 1910
User
Sterling P. Fergusson
1868 - 1959
User
Blue Hill Meteorological Observatory
1885-present
Cultural Region
Place of Origin
Place of Use
Dimensionseach thermometer, in frame: 31.7 x 2.4 x 1 cm (12 1/2 x 15/16 x 3/8 in.)
wet bulb, including "tail": 46 x 2.4 x 1 cm (18 1/8 x 15/16 x 3/8 in.)
storage box: 5.7 x 35.6 x 5.9 cm (2 1/4 x 14 x 2 5/16 in.)
wet bulb, including "tail": 46 x 2.4 x 1 cm (18 1/8 x 15/16 x 3/8 in.)
storage box: 5.7 x 35.6 x 5.9 cm (2 1/4 x 14 x 2 5/16 in.)
Material
DescriptionSeparate dry bulb thermometer (2008-1-0095a) and wet bulb thermometer (2008-1-0095b), apparently for a psychrometer. Each is fixed to its own steel frame with holes for mounting screws. The wet bulb (b) has a "tail" made of four pieces of string which hang down from the bulb; this is only loosely attached by a piece of cloth wrapped around the bulb.
Each thermometer is calibrated in Kelvin via black lines on the glass and numbers printed in black on a white strip screwed to the steel frame. Scale printed on both runs from 250 to 320 degrees [Kelvin] by tens; actual range of (a) as marked by hand on box is 239 to 329 degrees, and actual range of (b) is marked as 238 to 324 degrees. Additional temperature gradations [in Celsius] have been written in pencil on the white scale, ranging from 0 (equivalent to 273 on the printed scale) to 40 (=313): (a) has 0, 5, 10, 15, 20, 25, 30, 40; (b) has 0, 10, 20, 30.
The metal frame of (a) has a lot of water damage.
Each thermometer is calibrated in Kelvin via black lines on the glass and numbers printed in black on a white strip screwed to the steel frame. Scale printed on both runs from 250 to 320 degrees [Kelvin] by tens; actual range of (a) as marked by hand on box is 239 to 329 degrees, and actual range of (b) is marked as 238 to 324 degrees. Additional temperature gradations [in Celsius] have been written in pencil on the white scale, ranging from 0 (equivalent to 273 on the printed scale) to 40 (=313): (a) has 0, 5, 10, 15, 20, 25, 30, 40; (b) has 0, 10, 20, 30.
The metal frame of (a) has a lot of water damage.
Signedstamped on front of frame of (a): No. 27307 HENRY J. GREEN B'KLYN. N.Y.
stamped on front of frame of (b): No. 27308 HENRY J. GREEN B'KLYN. N.Y.
Inscribedwritten in pen on back of frame of (a): S.P.F. / August 20 / 1915.
written in pen on back of frame of (b): S.P.F. / August / 1915
FunctionA psychrometer consists of two thermometers placed alongside, one with an exposed bulb (dry bulb), the other covered in cloth and connected by a wick to a water reservoir such that it is always wet (wet bulb).
The thermometer wrapped in the wet cloth will display a lower temperature than the dry one in dry air because the water evaporating lowers the temperature of its bulb. This wet bulb temperature depends on the air temperature and the relative humidity of air (only in a 100% humid air both readings will be the same). One can determine the relative humidity of air with the readings from both thermometers and a table.
The thermometer wrapped in the wet cloth will display a lower temperature than the dry one in dry air because the water evaporating lowers the temperature of its bulb. This wet bulb temperature depends on the air temperature and the relative humidity of air (only in a 100% humid air both readings will be the same). One can determine the relative humidity of air with the readings from both thermometers and a table.
ProvenanceFrom the Blue Hill Meteorological Observatory.
Alexander G. McAdie
Date: 1915-1920
Object number: 1998-1-0831
French
Date: 1850-1890
Accessories: set includes: brass stand base; T-shaped tube; hollow tube with side neck; tube with ring stands; brass holder for two thermometers; one thermometer; glass tubes with brass bottoms (2); felt lined, fitted case
Object number: 3825
Hellige, Inc.
Date: 1949-1960
Accessories: wooden box
flexible black rubber tube with rigid white plastic connector at one end and a bulb-shaped glass chamber at the other end
metal pin with hardened red-rubber cap
Object number: 2003-1-0093
Date: 1890-1930
Object number: RS0501
French
Date: 1850-1890
Accessories: set includes: thermometers (2); brass stand base; silver vessels on a T tube (2); curved glass tube with cork; stand tube with side neck; stand tube with holder for curved glass tube; brass clamp for thermometers
Object number: 3824
English
Date: 1850-1900
Accessories: cracked glass cover
Object number: 1998-1-0752
Friez Instrument Division, Bendix Aviation Corporation
Date: circa 1956
Accessories: one used Taylor Instrument Companies paper chart and cardboard box; recording charts, Air Ministry, Meteorological Office, Form 4213, Barogram (18); one used "Self Recording Thermometer" chart. Richard Brothers Manu. PS Paris. "Blue-hill Meteorological Observatory"; one set of "Instructions for the Installation of Charts", Bendix Aviation Corporation, Friez Instrument Division, Baltimore 4, Maryland; Friez I.B. No. 165/Friez Part No. 509673-B
Object number: 1996-1-0190b
Negretti and Zambra
Date: circa 1890
Object number: 1998-1-1267b
R. G. Greiner
Date: circa 1850
Accessories: black cylindrical cardboard case
Object number: DW0792
Jules Tonnelot
Date: 1885-1900
Accessories: racks (2); box; instruction sheets
Object number: 1998-1-0857
Date: circa 1880
Accessories: mahogany case; hot cup manipulator; thermometers (2)
Object number: 3862