This ad shows a cross-section of what appears to be a U-935 
offered by C.S. Knowles and produced by Imperial Porcelain.
Note the transmission lines they were used on. 
                                                     
                                                                                          
                                                                    

Journal of Electricity, Power & Gas, January 1900

Journal of Electricity. Power & Gas, February 1900

This ad shows an artist's rendition of a U-935 and the 
Imperial Porcelain Trademark. Note that the ad states
 eight different styles are available.

Journal of Electricity, Power & Gas, June 1902

This Knowles ad shows what could be either a CD 315,
CD 321 or CD 333. Note the patent date of May 20,1902 
appears in this June 1902 ad. Sizes of the insulator listed 
go from 5" to 15". Anyone ever see a 15" one????

Journal of Electricity, Power & Gas, December 1905

One of the first New Lexington advertisements found. 
Note that the ad mentions "Crown" porcelain insulators.
Some porcelain collectors feel there may be a 
connection between Imperial's closing and 
the formation of New Lexington High Voltage.

Electrical Review & Western Electrician, January 1, 1909

This ad from New Lexington High Voltage shows 
what appears to be a M-4550. At the time of this 
writing, this insulator is unknown.