Here's an image of page 18 of Colin McIntosh's booklet "Canadian Insulators."

A few years ago I scanned a copy of Colin McIntosh's booklet "Canadian Insulators" for a Canadian collector. I have it as a PDF, if anyone is interested. Although the booklet refers to "The Glass Insulator in North America" (there's no copyright date, although it does say "Copyright Applied For"), Mr. McIntosh refers to the various Canadian insulators by "type" rather than CD number. Apparently he derived this type number from the Dominion catalog.

The CD 143 is probably his Type 7.

Here's what he said about Mr. Dwight on page 33:

Dwight - A Famous Name

On July 5th, 1912, Mr. Harvey Prentice Dwight died in his Montreal home. He was 84 years old. At the time of his death he was vice-president of the Canadian General Electric Company, & also president of the Great North Western Telegraph Co. In addition, he was a director of the Toronto & London Electric Light Company, President of the Birkbeck Investment, Security and Savings Company, and President of the Canadian Humane Society.

Mr. Dwight was regarded at the time of his death as the father of Canadian Telegraphy, for during a long and distinguished career of 56 years he served with distinction on most of the pioneer communication companies of Canada.

He entered the service of the Montreal Telegraph Company in 1847 (the year of its inception) as an operator, and a few years later came to Toronto as Western Superintendent. When the lines of the Montreal & Dominion companies merged in 1881 under the charter of the Great North Western Telegraph Company, Mr. Dwight became general manager of the system, and after 1893 filled the dual offices of President and Manager.

The insulator bearing his name is a short squat, heavy single petticoat design, with the words "Dwight" on one half mold and "Pattern" on the other. They are 3 1/2 inches high, by 2 3/4 inches wide, and have no drip points. There are at least 2 shades of aqua coloring, as well as purple. The design of these insulators is varied on the base rim, with 2 different finishes noted. Dwight insulators are smaller than the standard CPR and CNR beehives, definitely a different design.