Yost No. 1 Universal Vise (Patternmaker's)
Canadian Yeates-Gordon Co. ~ National Machinery & Supply Co.
Hamilton, ON

The Canadian Yeates-Gordon Co. was established in Hamilton around November 1910
sometime in 1911 by the parent company from Meadville, PA.

Strangely I can't find any information about the Meadville operation. Not coincidentally, that is where
GM Yost Co. built its new plant in 1908. Sept 29 of that year Yost was granted
US Patent 899,779 for improvements to the Emmert vise (patent 457,710) - two years after Joseph Emmert died. Another connection - Gilmore Yost had been manager at Emmert Manufacturing Co. (and would go on to
Columbian Hardware Co. in Cleveland, Ohio where he patented more vises).
By 1910 Yost was advertising its Universal Woodworkers Vise. The ad doesn't indicate that it was designated No. 1 or that the patent date was shown, but it may have been a simplified illustration.

Crossing the border...
In May 15, 1909 Yost applied for an equivalent Canadian patent, granted Jun. 29, 1909: number
119,203.
Was the Canadian Yeates-Gordon Co. then established in 1910 specifically to manufacture the Yost No. 1?
I can't find anything on the backers of that company except the creation, also in 1911 in Hamilton, of the National Machinery & Supply Co.

Incorporators included P. McC. Yeates, which gives us half the company name. Also of potential interest is one L. F. Stephens - in 1907 Yost had purchased the Snediker vise plant in Yonkers, NY, which also manufactured for the
Stephens Patent Vise Co. But nothing so far to connect the person and company.
At any rate, in 1910 or soon thereafter the Canadian Yeates Gordon Co. produced the Yost No. 1 in Hamilton. Finally, vise pictures

The patent hounds will notice that the casting indicates the US patent date, not the Canadian one.
Fast forward to Jan 2, 1913. National Machinery & Supply Co. is selling Yost machinist's vises, made in Canada. What happened to Yeates-Gordon?!

28 days later the same publication answers that question.

"The firm [National Machinery & Supply] was formerly known as the Canadian Yeates-Gordon Co."
However, since both firms were started
in 1911 within 6 months of each other that raises additional questions about why the two companies had co-existed and what motivated the change.
Vise manufacturing companies seem to rarely have had a straight-forward existence!
National updated the casting, which means anyone with a Yeates-Gordon Yost No. 1 can confidently say it was made from 1910 to 1911 - or a bit later if they had inventory to clear out.

Hmm, still the US patent date...
Another Canadian Machinery ad from July 1915 is identical to the 1913 machinist's vise ad (there were others in between).
But by 1916 National had a spiffy new logo, the machinist's vises bore the National name (and
looked identical to Rae vises), and Yost was not mentioned.

As for the Yost No. 1 Universal vise...

[Nuts, hit the 10 picture limit. Too bad.]
Edits: Based on new information.