[GreenKeys] underwater teletype

[Henry Minsky]

My father told me that he visited the Teletype factory in Illinois once,
on a trip for MIT, to look at a new model of teletype (one that
could do upper and lower case I think he said). He said that one of the 
things that
they had on display was a teletype submerged in a tank of water, operating
somehow. Something to do with a Navy specification that they work in
water. Does anyone know any more about this story?

Henry