VERY RARE  POCKET BAROMETER  FORECAST COMPUTER BY NEGRETTI & ZAMBRA  (patent 6276/15)

VERY RARE POCKET BAROMETER FORECAST COMPUTER BY NEGRETTI & ZAMBRA (patent 6276/15)

1000 euro

Country of manufacture

UK and Ireland

Category: Barometers & Meteorology

Description

VERY RARE

POCKET BAROMETER  FORECAST COMPUTER

BY

NEGRETTI & ZAMBRA

 

(patent 6276/15)

 

The most complex and rare pocket barometer forecast calculator,made by Negretti & Zambra, circa 1910/11.

 All parameters are adjustable by the winder crown and the outer knurled bezel. inputting all the known variables, wind direction, barometric pressure.

One exemplar was sold at 19 Jan 2006 by Lawrences Auctioneers of Crewkerne – for 1750£

Excellent and working conditions. (see all photos)

Without case.

diam. 50mm  ( 2″ inch)

 

     

                                                       

                                                               INSTRUCTIONS OF  NEGRETTI & ZAMBRA

POCKET BAROMETER FORECAST COMPUTER

By Paul Crespel

 

 

 

                             USE AS AN ALTIMETER:

The altitude scale is engraved around the outer edge of the case.  Holding the

instrument at such an angle that you can see the scale and the needle, turn the

back plate of the instrument to set the altitude either at your current known

altitude, or at zero if you are about to climb a hill or mountain and wish to follow

your progress.  At any stage you can read your altitude by holding the instrument

at such an angle that you can see the needle and the outer altitude scale.

 

 

USE AS A BAROMETER:

Although there is a zeroing screw on the reverse of the instrument, the best way

to calibrate your barometer for your correct local, or sea level reading is by

turning the back plate.  The movement is attached directly to the back plate, so

turning the back plate causes the sweep indicator needle to move.  The needle

will move clockwise or counterclockwise with changes in atmospheric pressure. 

Clockwise movement indicates increasing air pressure (improving weather) and

anticlockwise movement indicates lowering air pressure (worsening weather).

 

 

USE AS A FORECASTING COMPUTER:

Ensure your instrument has recently been calibrated to sea level pressure, then

turn the crown inside the hanging ring to adjust the “sea level” scale to match

how far above or below sea level you may have moved since calibration up to

500 feet each way.

Set the “direction of wind” setting at the bottom of the outer dial to the direction

of the wind.  This is done by rotating the outer bezel with finger and thumb.

Read the code letters in the windows for a “Falling”, “Steady:, or “Rising”

Barometer (three windows, read from the appropriate one),  and refer to the

back of the instrument for the interpretation.

The letters “S” (Summer) and “W” (Winter) are for the time of the year, the

former being taken from April to September inclusive, and the latter from

October to March inclusive.  

The forecast is for 12 hours, and the best time to take a forecast is 9am.

 

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IT Eppursimuove

Eppursimuove

Eppursimuove is located in the northwest of Italy. I deal with antique scientific instruments and their history. This passion has turned into a profession that leads me every day in search of ancient instruments that helped us to observe, measure, explore and know the sky and the earth. They still amaze and make us wonder, as they did for their original makers and users. For this reason they must be preserved and collected. Please feel free contact me if you need more information on listed items. Thanks.