Why are there 80rpm records instead of 78rpm?

Question

I have bought few 78 rpm records and i came across 80 rpm records under the Columbia label. And they look older than the usual Columbia record labels that we can find them in the 1940's Do you have any idea about the existence of 80 rpm records?

Answer 1

.......Emil Berliner's first disc gramophones were wound by hand at somewhere between 60 and 100 rpm. The 7-inch discs lasted a minute or so and had low sound quality. Berliner and his assistant Fred Gaisberg realized that unless the speed was governed, the gramophone would never be more than a novelty. Gaisberg visited a young mechanic who was making clockwork machinery in hoping to use it for sewing machines. This machinery was never successful in sewing machines, but was ideal for gramophones, and it rotated at 78 rpm. The mechanic, Eldridge Johnson, became a millionaire. Columbia made all its discs to run at 80 and HMV had its pioneer recordings produced between 68 and 92 rpm with the key of the piece marked on the label. You then tuned it on your own piano, using the gramophone's governor. These speeds all gradually settled into the standard of 78. ......

.......By no means all 78s were actually recorded at 78 rpm. Even in the late 1920s English Columbia was still using 80 rpm, and prior to about 1921 speeds were widely variable. Some of the audio tracks included in the Music hall section of this site were transferred at speeds as low as 74 rpm, and I have come across records where the speed was as low as 68 or as high as 84 rpm.
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Answer 2

no