A very early, interesting silver plated aneroid pocket barometer by Negretti & Zambra for Smith Beck & Beck c1864

Pocket barometer having 1⅞” silvered and die struck dial, standard meteorological terms, the barometric scale calibrated in inches of mercury with a range from 24” – 31” divided down to 1/20th, fine blued steel pointer, bevelled glass, barb index on a rotating bezel.

1st series Negretti & Zambra pocket watch sized finely poised movement driven from a single nickel alloy 1⅛” capsule. The bridge with steel brace and micro adjustment, blued screws, having inscribed service dates at “8/2/34” and “5/2/41” together with job numbers 661 and 5449 respectively, decorated primary chassis, sub chassis with cock and spindle mountings, the underside struck “19.” Inverted temperature compensation to primary lever. All contained within a semi barrel form ribbed silver plated brass case, pendant and bow, calibration port with sliding shutter to verso.

Presented in its correct round oxblood leather over timber, blue silk and velvet lined case, snap closure on a button release. Together with a contemporary hand written in ink altitude from pressure conversion chart, with later pencil notes relating to the Bolan Pass railway.

Condition: The subject of a full service, conservation, and calibration under laboratory conditions, see performance chart from dynamic test. The movement working exceptionally well with maximum noted error of 0.15” across the scale. 

The dial with some minor marks, otherwise crisp and clean. The brass case retaining a good proportion of its original silver plate, the travel case the subject of some restoration.

Comments: Analysis and study of these early instruments suggests that this is one of the very first aneroid pocket barometers manufactured by Negretti & Zambra who were the first to make such an instrument. It is possible that “19” is a serial number, though it may also be an early batch number. The question does arise, though, as to why, if such an early piece, it does not carry the Negretti & Zambra logo on the dial. Miniaturised at the behest of Admiral Fitzroy, these instruments would certainly have been much anticipated and most probably the first units were sent to retailers across the country as part of a publicity drive. The serial numbers as such would not have been important and indeed probably ignored. Indeed, it has been my experience that many prototype or early production instruments lacked visible serial numbers, and this would be no exception. A similar pocket barometer, marked “1,” carries the details of the retailer James White of Glasgow.

There is absolutely no doubt that these instruments were the work of Negretti & Zambra who patented the design for pocket watch sized instruments in 1861, and a near identical instrument in a silver case bears hallmarks for 1863.

The movements from this first series are exceptional and it is clear that a considerable amount of extra effort was taken in their manufacture and presentation. It is not known how many first series instruments were produced, however at time of writing the highest number/batch number known is 19. These would have been expensive to produce and from 1864 a second generation movement was introduced which, though still of very good quality, was noticeably less well finished with fewer embellishments and some of the finer points deleted entirely.

The provision of a swinging shutter over the calibration port is known on two of these first generation instruments only, and that might suggest that this was an extra fitted as a special order.

The Bolan Pass Railway

As this early watch sized pocket barometer had no altitude scale, an early owner created the inked altitude table included. At a later date, a different hand added a number of locations in pencil with their corresponding altitudes. These annotations were made in the course of a journey on the Bolan Pass railway in what is now Pakistan, as they refer to Kolpur, Sibi, Hirok, Peshi and Mach, all stations on this line.

With the very real fear of imminent war with Russian, the order was given in April 1885 to construct a light railway through the Bolan Pass from Sibi to Quetta, see the extract below from The Rise of Rail-Power in War and Conquest, 1883-1914 by Edwin A. Pratt (published 1915).