Capt. George C. Thomas grew 'Mary Washington' in his garden in Chestnut Hill, PA.

American Rose Annual, 1918, article Roses Retained and DiscardedBy George C. Thomas, Jr., pg. 121:

"Mary Washington. Growth small; bloom quite attractive; needs winter protection."

Note, winter protection needed in a Philly suburb. I doubt it MW would grow at all in a colder climate. I had MW in CA. I used to think the small, may-petaled flowers looked like coat buttons.

I suppose it would be too much to hope that this variety turned out to be the once-famous 'Herbemont's Musk Cluster'. The latter was said to be fragrant, but not musky. Also difficult to propagate.

Annual Report - The Mount Vernon Ladies' Association of the Union for 1891, p. 36
REPORT OF GARDEN AND GREENHOUSE COMMITTEE.
Your Committee respectfully report that examination of Garden and Greenhouse shows a very satisfactory condition in every department. The Gardener’s report gives the details of the management, improvements, expenses and income from this department, but we desire to note with especial and grateful appreciation the material assistance given the floral culture by the erection of a large and commodious propagating house by Mrs. Mitchell, Vice-Regent for Wisconsin, and a member of this Committee. The increased opportunity thus afforded furnishes the Gardener with all needed facilities for increasing his stock of plants and improving their quality. Your Committee suggests the advisability of allowing Mr. Whelan to advertise in some prominent magazines, especially to offset the conspicuous advertisements of the “Mary Washington Rose” for sale by other florists, by inserting a plain statement in the advertising pages of the “Century,” by which the public may know that the original rose is here, and may be had at the Greenhouse or by application to the Gardener.
(Signed) L. H. PICKENS
M. J. M. SWEAT
E. A. RATHBONE