Letter classification

I have classified the letters of the alphabet into 7 groups. Here are most of them. Within each group there is no significance to the order of the letters.

E, IT, NS, HUD, FLVWBG, POXCZ, JQY

I have omitted the four letters of my first name. Please complete the grouping by inserting them correctly. In case more than one answer makes sense, the 'correct' answer is the one I was thinking of when asking the question.

puzzle as spoiler space:

more space

M belongs in group 4 A belongs in group 3 R belongs in group 4 K belongs in group 5

Mark Brader (puzzle as spoiler space):

Mark Pilloff:

Right. Why?

Mark Brader schrieb:

The gentleman who would be most qualified to answer this question 'died of pneumonia in New York City on April 2, 1872, at the age of 80', so he can't respond. He 'was born on April 27, 1791, in Charlestown, just outside of Boston, Massachusetts. He was the son of [...] a pastor who was as well known for his geography as Noah Webster, a friend of the family, was known for his dictionaries.' (Source: rot13:uggc://jjj.zbefruvfgbevpfvgr.bet/zbefr/ zbefr.ugzy)

Have fun with the letter M below my name

Right.

Specifically, the letters are grouped by length, the rule being that one dot or the space from one dot/dash to the next dot/dash within a letter is equal to 1/3 of a dash.

Mark Brader schrieb:

Or, two dots are as good as a dash.

From the puzzle statement, it is clear that the groupings approximate letter usage frequency, although not quite. (why are O and Y so near the end?) Since Morse was obviously trying to optimize the code in this way, why didn't he do a better job? I imagine that his formula included a weighting for the extra length of the dash.

Or was the telegraph code like the QWERTY keyboard, designed to slow the operator down so the machine wouldn't jam?

suggests that Morse code was invented by Alfred Vail, one of Morse's partners, who came up with the letter frequencies by visiting a local newspaper and looking at a compositor's type cases.

The local newspaper was apparently in Morristown, NJ. But if Vail had been in California, he might have come across the 'California Case', a type-case with the famous 'ETAOINSHRDLU...' ordering. Ottmar Mergenthaler later used that ordering for his Linotype keyboard.

Hmm, the link that claims 'ETAOINSHRDLU...' derives from the 'California Case' doesn't seem to be too accurate. The so-called 'California Job Case' (which dates to the 1880s, long after the development of Morse Code) can be seen at:
http://members.aol.com/alembicprs/cjbcase.htm

This in turn was based on the 'Improved Job Case' of the 1870s:
http://members.aol.com/alembicprs/ijbcase.htm

Nothing about these type-cases suggests an ordering of ''ETAOINSHRDLU...' A comprehensive historical listing of type-cases can be found at:

This history explains how the codes for letters like O, Y, and C ended up lengthened in International Morse (blame the Germans' treatment of Vail's 'spaced letters':