Thursday, December 6, 2012

Thomas Armstrong & Brothers, Scientific Instrument Makers

During the second half of the 19th Century Thomas Armstrong (1829?-1890?) was a noted maker of scientific instruments with principal operations in Manchester, England.  Having been trained as an optician, his initial interest was in providing optical devices to a variety of clientele.  However, he rapidly expanded the firm into producing instruments in many new scientific areas.

Joseph Armstrong, Thomas' father, had started the family business as a jeweler and silversmith. Thomas, being the eldest son, joined his father's firm and started incorporating his field of expertise into the firm's product offerings.   After his father's death Thomas took his brother George into the business as his partner and went by the name Thomas Armstrong & Brother in 1868. At some point after that the two Armstrong brothers also made their other brother, Alfred, a partner and the firm was renamed once again to be Thomas Armstrong & Brothers.  By this time they were providing compressed gases, meteorological equipment and other optical equipment to a wide variety of clients.  In 1891, based upon the success of the firm and the quality of the products that they were producing,  they were awarded substantial contracts with the military, and many other government agencies in addition to their other clientele.  Frank Armstrong, Thomas' son, joined the firm in the 1890s.  The firm continued to grow and provided a substantial variety of devices used in World War I.  For a more complete biography of the family of Armstrong scientific instrument makers refer to an article on Thomas Armstrong at the  Manchester Museum of Science and Industry.

I had acquired a pocket aneroid barometer labeled Thos. Armstrong & Bro. a number of years ago and found it to be quite well made and still functioning well.  For those of you who are not versed in the variety of barometer technology there are a number of ways to measure barometric pressure.  

Early barometers were constructed using a column of mercury of about one meter in length.  Furthermore, for these barometers they were required to be kept level. This was difficult to accomplish at sea. 

Subsequently, the French developed the aneroid barometer.  An aneroid barometer which was a thin long metal tube (usually coiled in order to take up less space), closed at one end and with a membrane on the other end. With a vacuum inside the tube and a clockwork gearing mechanism to measure minute movements of the membrane the device could detect very small changes in the atmospheric pressure.  Furthermore, this device was not required to be level in order to give an accurate reading. There are quite a variety of aneroid barometers that have been made. Needless to say, the smaller the tube, the more precise the clockwork gearing mechanism must be to measure the movement of the membrane accurately.  A small accurate pocket barometer is a device to admire.

Finally, the bargraph was developed. The heart of this mechanism was a belows mechanism that was connected to a levered arm with a pen on its other end. It was constructed such that a small movement of the bellows, which resulted from a change in barometric pressure, would result in a larger movement in the pen at the end of the arm through the mechanical advantage of placement of the fulcrum on the levered arm.  Additionally, the bargraph was fitted with a rotating drum covered with graph paper such that the barometric pressure was recorded.

Barometers are used for a variety of purposes. Principally, a stationary barometer will indicate important information for weather prediction.  A portable barometer can be used to measure altitude.  I will discuss each of the barometer types in a later post.

Subsequent to acquiring the Armstrong pocket barometer, I was fortunate to acquire other types of barometers including a number of mercury banjo barometers, a bargraph and a number of other aneroid barometers.  Restored mercury barometers are expensive. Having acquired an unrestored mercury barometers, I have now restored two of my banjo barometers and I am working on the third one.  

Other Armstrong instruments I have acquired include:
A Syke's hydrometer which includes the standard ball and weights, thermometer, and slide rule.  These were used by guagers to measure the alcoholic content of spirits in order to collect the excise tax for the government.  This is again a story for another post.

An automobile clock.

A wall clock




Travelling silverware set

I will post some images of these items as I get around to it.