Outdoor meteorological mercury minimum thermometer on a white porcelain plate mounted on a wooden back.
The scale is printed on a raised porcelain plate from -20 to +120 degrees Fahrenheit, single degrees are etched
on the thermometer tube. Printed on the base plate and surrounding the Royal Coat of Arms (because the
maker had the Royal Warrent) is CASELLA’S PATENT MERCURIAL MINIMUM 23 HATTON
GARDEN LONDON, and No. 275 which is also etched on the thermometer tube, showing that it is the original
tube. The side chamber is intact and faintly scratched on the scale plate is the name Dr Fox. It was patented in
1861 by Louis Marino Casella, son of the noted instrument maker Louis Paschal Casella (1812-1897), who did
not recommend the minimum thermometer invented by his son. It is in good condition, considering that it was used
outdoors. Overall width 13.5 inches (34cms). English circa 1865. Ticket Price £260. Email me here
See: British Patent Specification No. 2100 of 1861
L. Casella, Illustrated and Descriptive Catalogue of Surveying, Philosophical, Mathematical,
Optical, Photographic, and Standard Meteorological Instruments, London 1871, p 14*
Two antique slide rules made of boxwood.
From the top:
A four sided excise officers slide rule of unusually large size (the standard size is the lower example). Under one
of the four sliders the stock is stamped RIX. J. Rix was working in London between 1750 and 1760. Each slider
has a brass piece let into each end. This prevents wear when two sliders are used in one groove. This modification
was due to Charles Vero (or Verie) and prevented the calculations going off the end of the slider. The stock is
marked with various gauge points such as AG (ale gauge) and Seg. Lying (segments lying). The latter being used
to calculate the amount of alcohol in a barrel when it is lying on its side. The reverse of the slides are marked with
numerous gauge points, divisors and Variety Lines, which were used to take into the account the different shapes
of barrels. Length of stock 18 inches (45.5cms). It is in very good condition. English circa 1750-60.
Ticket price £590.
The lower slide rule is also a four slider gauging rule with Vero’s modification, and similarly marked. It was made
about 1780 and is signed “EDWRd ROBERTS Maker Dove Court Old Jewry LONDON” (Roberts was
working 1749-84, 1788-96). I suggest that his four years absence from the records may be due to him being in a
debtors prison, a common enough occurrence in the eighteenth century. However, Roberts was clever in one
respect, he had his business in the same building as him primary customer, namely Customs and Excise.
Length of stock 12 inches 30.5cms. It is in good condition. Ticket Price: £490. Email me here
See: Bulletin of The Scientific Instrument Society, No.3, 1984, pp.3-4
G.Clifton, Directory of British Scientific Instrument Makers 1550-1851, London 1995, pp.233-234
