This is from an old post I did about Helpful Hints brochures. Perhaps this will help some.
In reviewing my collection of helpful hints brochures, I noticed some
> differences that the group may find interesting.
>
> The "older" version (jodhpurs and jacket)shows a hammer block on the
> sideplate and not on the cut a way of the gun. Inside the S&W logo
> says TRADE MARK and REG US Pat.Off. Also the second sight picture
> shown shows what appears to be a round call bead front sight even
> though the cut a way is a model 10 with a round blade front sight.
> There is a comment at the end of the cleaning and oiling paragraph
> that mentions that S&W guarantees their arms only when used with
> factory ammunition of the type plainly stamped on the barrel. There
> is no "Marcus Registradus". There is a cylinder stop screw shown and
> there is wording under the sideplate about S&W RUGGED design. Marked
> M.J.O'M.CO. PRINTED IN U.S.A.
>
> Then we move to the one with the officer without the jacket and
> jodhpurs. I have several different versions, there may be more. I
> am listing them in the order that I feel is correct, I am open to
> corrections.
>
> 1) Same size as before 7" by 7 3/4". Hammer block now shown on the
> cut a way and not the sideplate. S&W logo inside now just says TRADE
> MARK. Second sight picture shows square type front sight. No
> ammunition comment under cleaning and oiling. Now says MARCUS
> REGISTRADUS. Marked S&W Printed in U.S.A. 7-51.
>
> 2) Size now 7 1/8" by 6 5/8". Cylinder cut a way now shows extractor
> spring and center pin spring. Cut a way picture of gun now slightly
> smaller. Sight pictures from 7-51 version have been reversed. New
> paragraph added regarding SIGHT ADJUSTMENT and how many clicks to
> accomplish elevation and windage changes. Wording under SAFETY
> changes slightly and refers to handling by competent persons. Front
> sight shown is now a ramp not a round blade. Hammer design is
> different.
>
> 3) Size now 7" by 7". Cylinder stop screw no longer shown. Rugged
> design paragraph under picture of sideplate no longer printed. Cut a
> way is smaller still with tip of barrel about 1" from edge of
> phamplet.
>
> I also have one that is specifically geared towards the Centennial
> Revolver.
As some additional information, the police officer in the jodhpurs is Officer Ray J. Nowka of the Los Angeles Police Department. In the early 1930's he set a new police record for target shooting at the Camp Perry National matches, shooting a Smith & Wesson .38 M&P and scoring a 281 out of a possible 300. His likeness was used in the early Helpful Hints brochures, however, I do not know the exact date. The later photo was that of long time S&W employee Harold Devine.
