A simile is a comparison between two typically unlike things (using either "like" or "as" to create the comparison). For example, the sun is like a golden coin is a simile because it compares the sun to a coin. Another example, this time using "as"," is: she face is as bright as the sun. Here, a girl's face is being compared to the sun.
In regards to chapter ten, of Harper Lee's novel To Kill a Mockingbird, three similes can be found.
"Jem gulped like a goldfish." Here, Jem's gulping is compared to the gulping of a goldfish.
"We could see him shiver like a horse shedding flies." Here, Tim Johnson, the rabid dog, action of shivering is being compared to that of a horse.
"He walked quickly, but I thought he moved like an underwater swimmer." Here, Atticus' pace towards Tim Johnson is being described as slow--like the pace of a swimmer underwater.
That said, one cannot simply look for the words "like" or "as" to find a simile. Sometimes, the words are used as descriptives (meaning they are describing something and not being used in a comparison).
For example, “Atticus is a gentleman, just like me" is not a simile. Jem is not comparing himself to something; instead, he is describing himself as a gentleman.
Similes seem to come easily to Scout, as many Southern colloquialisms often contain the words like or as in forming a comparison between two unlike people or things.
--In the opening chapter, Scout describes Maycomb ladies as being "like soft teacakes with frostings of sweat and sweet talcum." (Ch. 1)
--In what seems an odd comparison for Scout to make after having been punished by Miss Caroline, Scout remarks about her, "She looked and smelled like a peppermint drop." (Ch. 2)
--Scout observes that while Miss Caroline reads a story to the class, some of the kids are "wriggling like a bucketful of catawba worms." (Catawba worms crawl across certain tree leaves, consuming the leaves at a mad pace.) (Ch.2)
--Of Mrs. Dubose, Scout says,
Her mouth seemed to have a private existence of its own. It worked separate and apart from the rest of her, out and in, like a clam hole at low tide. (Ch. 8)
--Ever the gentleman, Atticus tips his hat to Mrs. Dubose whenever he passes her house and she is outside.
"Good evening, Mrs. Dubose! You look like a picture this evening."
--After Jem retaliates against Mrs. Dubose for her insults to him, his father learns what has happened. As he stands at the hat rack in the hall, Atticus calls harshly to Jem. After hearing him say her brother's name, Scout remarks, "His voice was like the winter wind."