I guess they could have represented each of the romaji letters with the dots and dashes. 

I'm too lazy to search on the Internet...does anyone just know off the top of their head?

https://ja.m.wikipedia.org/wiki/%E3%83%A...6.E5.8F.B7
Apparently yes. It's kana-based.

Of course. That was a big part of how Admiral Tougou crushed the Czar's navy, which lead to 欧米 countries recognizing the military strength of Imperial Japan.