I should do so

[germanictamoon]

Hi all,
I am quoting the very first lines of 'The Valley of Fear' by 'Arthur Conan Doyle'. Lines are as follows:
"I am inclined to think--" said I
"I should do so," Sherlock Holmes remarked impatiently.
I am a bit confused about the meaning of the sentence ''I should do so''. To me it means that here Sherlock Holmes finished the sentence for the original speaker because Sherlock thinks that the speaker was going to say that 'so' thing should be done by Holmes and impatiently Holmes finished the sentence himself. But the translator of this book in my native language translates this sentence that can be again paraphrased in English as 'let me think instead' or 'leave it( thinking) to me'.
What is the real meaning of the sentence ''I should do so'' here? Who is right, me or translator ?

 

[entangledbank]

Holmes isn't saying that "I (Holmes)" should do so: he is saying "if I were you, Watson, I would do so", that is he is advising Watson to do so - to think. Watson begins by using 'think' in one common meaning, "believe; have an opinion". Holmes jumps on this and criticizes him, because he knows Watson has not really thought (in the other common meaning: "reason; concentrate; work out"). He means "don't just have an opinion, but really think about it".

Perhaps this sort-of pun on two senses of 'think' isn't available to your translator, so it has to be phrased less exactly.