Count Olaf: I must say, you're a gloomy looking bunch. Why are you so glum?
Klaus Baudelaire: Our parents just died.
Count Olaf: [nonchalantly.] Ah, yes. How very dreadful. Wait, let me do that one more time. Give me the line again while it's fresh in my mind.
Klaus Baudelaire: Our parents just died?
[Olaf pretends to be shocked.].
Stephano: I've been bitten forty-three...seven hundred times. Mostly on the face. A lot of this has been reconstructed but I think they did a great job even though my moustach is a tad askew.
Klaus Baudelaire: Did Ike die in a fire?
Aunt Josephine: No, silly child. He was eaten by leeches.
Violet Baudelaire: It's a suicide note. Why are you checking her spelling?
Klaus Baudelaire: She said her greatest joy in life was grammar. Why is she making these mistakes?
Violet Baudelaire: Well, if you were about to jump out a window, you might make a few spelling mistakes too.
Answer: A magnifying glass concentrates all the light that goes through it at its focal point, and it is this focal point that needs to be placed on the object which one wants to set on fire. The distance of the focal point to the lens depends on the magnifying glass characteristics, and it is more than likely that Count Olaf chose a glass where the focal point would be situated exactly "37 blocks" away from his house, that is, at the Baudelaire's mansion. When trying to set on fire an object much, much closer, the glass would concentrate much, much less energy, and would only be able to set on fire easily burnt objects, such as thin paper.
AnthonyA