This shutter is essentially a Prosch Triplex Shutter with a second spring on the back to obtain faster exposures.
The G. Gennert 1895 catalog (Descriptive Catalogue of Photographic Apparatus and Supplies, G. Gennert (New York, NY), dated Jan. 1, 1895, p.30) states that the Prosch Athlete Shutter is an alteration of the Triplex Shutter, which alteration may be had for $5.00 over the price of the Triplex.
References:
Catalogue of Photographic Goods and All
Articles Pertaining to Photography, The Scovill & Adams Co. (New
York, NY), undated c.1895, p. 41
Catalogue of Photographic Apparatus, Rochester Optical Co.
(Rochester, NY), May 1897, p. 53
Illustrated Catalogue of Photographic Equipments
and Materials for Amateurs, E. & H.T. Anthony & Co. (New York, NY),
November, 1898, p. 70
Catalogue No. IIII of Professional and Amateur Photographer's
Supplies, Wm. F. Uhlman (St. Joseph, MO), c.1901, p. 22