How Old Is My Gurley?

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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!


1871manual.JPG (67980 bytes)

1874manual.JPG (71244 bytes)

1879lethead.JPG (59450 bytes)

1880billhead.JPG (63938 bytes)

From 1871 Manual

From 1874 Manual

From 1879 Letterhead

From 1880 Billhead

1897manual.JPG (91829 bytes)

1901manual.JPG (120094 bytes)

1909manual.JPG (86451 bytes)

1912manual.JPG (83794 bytes)

From 1897 Manual

From 1901 Manual

From 1909 Manual

From 1912 Manual

1920catalog.JPG (82350 bytes)

1921manual.JPG (120274 bytes)

From 1920 Catalog

From 1921 Manual



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