From Insulator Wiki (Wikilator)
Location: Boston, MA
Manufacturer: Unknown. Possibly The Standard Glass Insulator Company, location unknown, or American Iron Glass Pipe and Plate Company, Haverhill, MA.
Production Dates: Unknown. Probably circa 1885.
Lawrence B. Gray was listed as a mold maker in Boston City Directory listings during the 1880's, and was granted two patents for "presses for molding glass insulators." Mr. Gray appears to have been directly or indirectly associated with several well known names in insulator manufacturing, including the National Insulator Co.; Standard Glass Insulator Company; American Iron Glass Pipe and Plate Co.; American Insulator Co.; and Samuel Oakman. These patents were used in the production of National Glass Insulator Company insulators most likely by the American Iron Glass Pipe and Plate Company works at Haverhill, Massachusetts.
The CD 138.2 design, which is the only shape with this primary embossing, was produced by both National and Standard.  It is possible that the three known Lawrence Gray examples were among the few original prototypes and/or samples that led to the eventual mass production of the embossed National and Standard CD 138.2's. It is possible the Haverhill plant produced these units with only the "MANUFACTURED BY LAWRENCE B. GRAY'S PATENT PROCESS" embossing. However, the unusual color, an odd bluish lavender, in which these insulators were manufactured does not compare with the uniformity of light aqua or light greenish glass in which National specimens are known. The unusual blue gray glass color also leads one to theorize that a glass batch was not specially prepared for a large run of Gray insulators, but possibly "borrowed" in a small amount from a glass batch designated for other utilitarian glass items. The shape of the CD 138.2 Lawrence B. Gray is similar to the style produced by The Standard Glass Insulator Company, with large base lettering like the Standard units. The Standard Glass Insulator Company advertised their insulators as being "Manufactured By Lawrence B. Gray's Patent Process", so there could have been an association between insulators made by Standard and the scarce units lettered with the Lawrence B. Gray Patent Process reference. Mr. Gray may also have desired to try his own hand at making insulators at some other location.
Of the three known examples with this embossing, two are confirmed to have been picked from Danvers, Massachusetts. Although not confirmed, the third likely came from the same area.