| A frequently asked
question is, "How old is my Gurley instrument?". In some
cases this is a very simple question to answer, in others much detective
work is needed. The Gurley company was started in 1845 so
the range of possibilities is quite large. As a simple guideline
for determining age, the following ideas are offered.
For instruments made after
1908, generally the first two digits of the serial number represent the
year of manufacture. As an example, a serial number of 29288 would
have been made in 1929. An exception to this is that not all
levels follow this scheme and there is no apparent definitive scheme for
levels.
There are some instruments that
have a letter coding according to the following:
W
A N T G U R L E Y
0
1 2 3 4 5
6 7 8 9
It is believed
that most instruments, if not all, that use this coding were made for a
government contract(s).
For earlier
instruments dating them can be quite difficult. One way is to go
through old Gurley catalogs and look for matches and attempt to narrow
the age to a range of years. Another method is to look for hidden
marks where someone may have dated the instrument when it was being
made. These hidden marks can be difficult to locate and it is not
recommended that you tear apart your instrument. Also, some of
these hidden marks may be the results of later repair work.
There are a couple
of significant design changes that can also help to date Gurley
instruments. In 1880 Gurley switched from hand engraved plates
with fancier script to mechanical pantograph for engraving. Also,
"Troy NY" was moved to the North position. In 1885
Gurley adopted the spring opposed tangent screws and the "straight
A" telescope standards predate 1885.
Another thing to
look for are early patent marks on certain parts of the instruments such
as Beaman's stadia arcs, latitude bubbles, and auxiliary
telescopes. These dates would show up on specific parts for
several years after the initial patent.
Another method to
obtain approximate dates is to compare a picture of the Gurley shops on
the label in the case with pictures of known dates. Presented
below as thumbnails are 10 pictures of the Gurley shops that range from
1871 to 1921. These pictures are from various manuals, catalogs,
letterheads and billheads that can be dated. Some of the
differences in the pictures are very obvious and others are not so
obvious. The differences to look at include the following:
angle of view of building, size of the building, number of buildings, is
there a flag, where is the tip of the flag, are there balconies on the
third and fourth floor, does the third floor balcony have a cover, is
there a horse drawn cart, and is there an awning on the ground floor
entry?
Determining
the exact age of an instrument can be a very time consuming and
frustrating task, but these general guidelines may be useful to
you. Good luck!
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