>31st and Chestnut Streets
From google maps, South 31'st street intersects Chestnut street on the corner of the block with street address 3107, so yes.
>controls the production of the Pennsylvania Lawn Mower Works
I lost the reference, but the same article that mentions William W. Supplee's retirement, mentions that Supplee has exclusive rights to distribute the Pennsylvania Lawnmowers, foreign and domestic...
Interestingly, there are 3 issues of Hardware Dealers magazine that have advertisments for both companies side by side. This alone makes me wonder, why advertise both if they were the same company? Farm Implimenty News (#27) also lists both companies in the same index's at the same time.
> last listing in Philadelphia city directories ...1900
They are in Phil at least until 1916, Coal Age mentions them in a contract award, and lists the 31st & Chestnut address.
Seed Trade buyers guide lists them only as in Philadelphia (1936)
However, I find nothing after that date..
A 1949 reference mentions that the 'PHILADELPHIA COLONIAL' is made by Coldwell-Philadelphia Lawn Mower Co., Newburgh, NY. So, perhaps they were gobbled up... (Coldwell lawnmower goes back to 1891)
(Coldwell- Philadelphia was bought by Toro - 1950)
For the other company, Hardware Age #157
Sometime before 1957 : Pennsylvania Lawn Mower Div American Chain & Cable Co
Not entirely difinitive, is it...