Hi Ty, just to add further to the story, I found this whilst researching this morning:
It is often said that the English Rotoscythe, first made by Power Specialities of Maidenhead, later of Slough and then taken over by J. E. Shay of Basingstoke, was the first practical rotary mower. J. E. Shay Ltd, a large concern with major interests in fork-lift trucks, had been founded by Sir Emmanuel Kaye and John Sharp.
Some of the very early Rotoscythes were electrically powered. The inventor of the Rotoscythe was David Hamilton Cockburn, a recognised engineer who had already had patents granted to him in other engineering areas before he applied for the first "Rotoscythe" patent on 29th February 1932. That first patent was granted on 29th December 1932 - GB 385,473.
However, a design of Joesphus Miller of Louisville, Kentucky, USA, pre-dates the Rotoscythe. The machine was sold by the Louisville Electric Manufacturing Co under the name Pioneer. US patent 1,831,681 was applied for by Miller on 19th October 1928 and granted on 10th November 1931. The machine featured a horizontal cutting blade directly connected to a vertically mounted electric motor. The height of cut of the described lawnmower was adjusted by moving the entire motor/blade assembly up or down as required.
The blade was described as being either a single one sharpened at its "diametrically opposed" ends as in many modern rotaries, or as a transverse bar to whose extremities cutting blades or circular cutting disks were attached. The mower seems to have cut (and at least one example apparently still cuts) grass adequately.
Unlike the Rotoscythe, the Louisville mower did not feature any grass collection system nor were the cutting blades completely surrounded by the deck (or otherwise) of the machine. The patent drawings bear a resemblance to the rather later (I presently assume) and interesting Australian Tecnico electric lawnmower.
Also see US Patent 1,992,494 applied for by Walfred Lundin of Maplewood, Oregon, USA, on 7th March 1932 and granted on 26th February 1935 for a more advanced electrical rotary mower which featured a castor-wheel at the front. I do not presently know whether this machine was ever built, either as described in the patent or at all. The well-known UK Hayter concern was also making rotary mowers from about 1947, as you have addressed Ty.
