This interesting saw gets more quixotic the more I learn about it, and I now have more questions than answers. The saw is a skew back, 7 ppi rip saw, 24” edge length, with beech handle having 4 brass saw screws, including raised brass medallion with maple leaf (marked “Trade Mark”), and a patent date of Dec. 21, 1869. The saw plate has two mostly clear etchings. One marks it as Model “No. 4”-- a “patent ground” product of “Shurly & Dietrich, of Galt, Ont. / Spring Steel / Warranted.” (all on an etched maple leaf). A larger etching toward the handle, and set a 45 degree angle has a ribbon with the large proclamation, “SECRET TEMPER.” Below this is text, “Registered”. / “The superiority of this saw co????? is in being tempered by our secret process.”
I have learned that Shurly-Dietrich (as a named company has history that goes back to 1873s and through the early 1900s until 1930, when it was acquired by Atkins. Note that the 1869 patent date refers to a patent issued to David Munger (No. 98180) having to do with the design of split nuts. This patent was used by a number of companies (eg Harvey Peace, Richardson, Wheeler, Madden & Clemson) as well as Shurly-Dietrich. It has nothing to do with this saw (which clearly dates to the 1900s).
This saw (No. 4) is described in a Shurly-Dietrich 1920 catalog found online on Gary Roberts' site (Toolemera). It was a mid-level model, described as having a generic maple leaf etching and made of spring steel. That catalog makes no mention of the Secret Temper. It is also listed in earlier catalogs (1896, 1901, but not in catalogs after the merger with Atkins about 1930.
Information about the Shurly-Dietrich “secret temper” business is hard to find (but it it was out In the open, it wouldn't be “secret”--right)? In the catalogs after 1920 “secret temper” is mentioned mostly with regard to large crosscut saws. The 1920 catalog listing for the “Pacific King” crosscut saw (the only secret temper saw in that catalog) states, “….this saw is tempered under our secret chemical process, which toughens and refines the steel, which gives a finer and keener cutting edge.” The saws that earn the “secret temper” process tend to be made of Shurly-Dietrich's best steel, "Razor Steel". I have been unable to find any hand saw (with Spring or Razor steel) that is listed as having “Secret Temper.” From all of this I conclude that this saw was most likely made after 1901, and before 1930—and probably between 1920 and 1930. It is in good shape, with a straight, moderately tarnished blade, good etching and is reasonably sharp. Apparently it is a scarce example, especially with the "Secret Temper" Etch. Good+
Price - $60.00