'The insolence of the man!' cried Holmes in fury.

'The arrogance of revealing his plan to me in advance, not to mention the impudent swagger of signing it with his own name! Moreover, today is the sixth. If we are to avert catastrophe, we must make the utmost haste! Watson, the note is self-explanatory; please make the necessary arrangements at once.'

He handed me a piece of paper, marked with the following legend:

28 7 90 34 78 61 16 15 88 39 15 8 53 16 8 7 31 34 16 49 84 57 60

59 8 26 16 38 42 75 18 22

Puzzle as I might, I could not make head nor tail of it.

Can you assist Watson in deciphering the mysterious message?