The more things change...
Serious power! Remember this was before tuned circuits became common (google 'syntony oliver lodge'). Even allowing for the sensitivity of a balanced carbon spark gap, you need to move a carbon rod or have a magnetic field strong enough to change the position of the discharge. He must have been in the same building...
The tuning issue is one of many snags that Marconi ran into, and with a government contract on the line, he made no small effort to keep the technological troubles under wraps until solutions could be found.
That said, I am a second language English speaker and haven't even completed English as a second language in high school.
The original spellings of the verb forms are dis, dissed, disses, dissing.
I think it's only normal for people to end up spelling it 'diss', especially as the original word it was derived from becomes less known.
True, but you'd think a publication like NewScientist would strive for (some sense of) correctness in terminology selection.
Also see: http://www.grammarist.com/spelling/dis-diss/