Originally Posted by MrBarnett
In February, 1889 he wrote a letter to Wilfred Meynell in which he claimed 'I have shaved with a dissecting scalpel before now.'
Is that it, is that the evidence that Thompson was carrying a 'knife' in the autumn of 1888?
Yes. "before now" refers to things that happened before, meaning "prior to", the time "now".
dissecting scalpel, a small straight knife
with a thin sharp blade used in surgery and dissection.
shaved = razor sharp, as in"my knife is nice and sharp".