W. & L. E. Gurley Dating

Here you will find information about how to date your W. & L. E. Gurley antique survey instruments.
Gurley instruments can be tricky to date because not all Gurley instruments are serialized.  Gurley started using serial numbers in November 1908 and the serial number actually contained the year the instrument was manufactured.  The serial numbers can be found on levels, transits, and some of the larger surveyors' compasses.

Any level, transit, or larger compass manufactured after November 1908 should have a serial number on it located on the level bar, face of the compass, I have seen them on the standards, or on the vernier plate.    Gurley may have started to use serial numbers because of a second location that was opened in Seattle in 1908 creating a need to keep track of the instruments sold out of both locations.  The serial number log books for Gurley are currently held at the New York State Museum.  The first instrument listed in Gurley's serial number log book is number 81.  Since Gurley did not start using serial numbers until November 1908, this was not the first instrument made by Gurley that year but it was the first serialized instrument made in 1908.  The first fifty instruments serial numbered 81-850 were all destined for the Seattle branch.  

The first digits of the serial number indicate the year it was made; i.e., serial number 9254 was the 254th instrument made in 1909.   

Two examples are shown below:
The image on the left is serial number (sample 1) 13601 which would be the 601st instrument made in 1913.  The image on the right is serial number (sample 2) 14725 which would be the 725th instrument made in 1914.

Click On Image To Enlarge
Gurley Serial Number Sample 1
Gurley Serial Number Sample
Gurley Serial Number Sample 2
Gurley Serial Number Sample
Gurley also used a different serial number system believed to have been implemented for Government contracts.  Those substitute letters in the serial number are broken down as follows: An example of this type of serial number is TL1258 which indicates this instrument was the 1258th instrument made in 1937.


We have been notified and have done some research and this information may not be entirely correct in all cases. We found a serial number in this format and the design of the instrument was not released until many years after the date we calculated using the example below.  Please use with caution and make sure your design matches what was available at the time.

Gurley Gov. Serial Number Example
Gurley Serial Number Sample

***Special Note About Gurley Levels***

Gurley levels were serialized starting around 1900. William Bastedo, who ran the Level Department began the practice of serializing the levels, perhaps on his own. He had a numbering system that was not the same as the system later adopted by Gurley in November 1908 and described above. If your level has a serial number on the bottom side of the tripod plate it was probably made between 1900 - 1908. Remember the plate could have been replaced.  We do have some copies of the Gurley shop records and may be able to help you research it a little more.


Dating Gurley instruments prior to 1909 can be very difficult.

The best source for dating information on Gurley transits made before 1909 is a book called "The Complete Guide to Early W. & L. E. Gurley Transits".   This book describes the best methods for dating Gurley transits that were made before 1909.  The information in the book discusses engraving, Case tags, design changes, etc. and while this book is specifically written about the transits some of design changes described can also be used to help date some of the larger compasses and levels. 

In the book you will find Gurley history, employee information, catalog and manual information, patent information, over 500 illustrations, and descriptions of Gurley transits and options.  Demonstrated are the best known methods for dating transits made between 1845 and 1908, before serial numbering, using design changes, patents, options, and other indicators. Additionally there is a Glossary of Terms to assist you in your research. Transits are broken down by model with images to help guide you through the dating process. Inside you will find complete sections that cover the Surveyors’ transit, Engineers’ transit, Vernier transit compass, Light Mountain transit, Reconnaissance transit, Explorer transit, and the Builders’ transit.

Hover Over The Images Below And Click On Icon To See Many More Sample Pages.