Letter from Charles Vernon Boys to Robert Stewart Whipple

Boys 'can't very well show my solid prisms again at the R. Soc. soirees' as he 'had them there last May & June and I had a Dent's dipleidoscope'. He suggests Whipple could 'show your collection of 5 and you might have my 2 also ...'. The one Whipple let him borrow is interesting; Boys judges it 'to be an earlier attempt of Bloxam's. It is not so good in any respect as is hollow prism'. He then goes on to describe the theory and manufacture (with sketch).