William E. and Lewis E. Gurley, brothers, were born in Troy, New York; William in 1821and Lewis in 1826.  In 1839, William graduated as a civil engineer from Rensselaer Institute.  After going as far west as Michigan seeking employment as an engineer and finding none, he returned to Troy and went to work for five years as a foreman for Oscar Hanks, a surveying instrument maker.  In 1845, William formed a partnership with Jonas Phelps under the firm name of Phelps & Gurley.  In 1844, Lewis Gurley had become an apprentice to Jonas Phelps.  Then from 1847 to 1851 Lewis Gurley attended the Union College in Schenectady and graduated with a Bachelor of Arts degree.  In the fall of 1851 Lewis Gurley was admitted into partnership with his brother William Gurley and Jonas Phelps under the firm name of Phelps & Gurleys.   In 1852 the Gurley brothers purchased Jonas Phelps' interest in the business and the firm became known as W. & L. E. Gurley.

Reference:  Smart, Charles E.   The Makers Of Surveying Instruments In America Since 1700   Troy, New York:  Regal Art Press.   1962