"The ignition of the gas in the inlet pipe by a flame in the cylinder left over from a former explosion after the inlet valve opens, or by too weak a mixture, by dirt in the carburettor, a leaky inlet valve, or too small a fuel pipe. I have known an open throttle and late spark to cause backfiring. If with low speed and a little more feeding of fuel the backfiring continues, you must look for carbon deposits in the combustion chamber."
"Many persons are puzzled by explosions in the muffler. Are you?"
"I learned from my instructor that they are produced by an unignited charge entering the muffler and being fired by the hot gases from the next explosion in the cylinder. This does no harm, and if the muffler is strong is a good thing, for it blows out the smoke and dirt that have accumulated."
"The trouble with—with—him, you say, was the lack of fuel."
"Yes, but he might have had plenty of gasoline and found the engine dead on his hands. Water or dirt in the carburettor plays the mischief."
And so the questions and answers went on—so many of them that you would find their reading tedious. The pitiful part of the whole business was that, as I have said, Chester could have made clear everything asked as well as his chum and the chum knew it. It was a pathetic attempt to hold their minds from the one gruesome, oppressive truth.
But they were too manly to shirk their duty. Nothing was to be gained by turning from that which sooner or later must be faced. Two of the saddest calls upon them must be answered.
"Shall we search for the body before letting his father and mother know?" asked Chester, when they had passed McKown Point and were entering the harbor of Boothbay.
"I don't know what is best. They will soon hear of it and will be frantic until the body is found."
"It is not likely to come up and float for several days, and there's no saying where the currents will take it. A few years ago a fisherman was drowned off the eastern side of Squirrel and was found a week later several miles up the Damariscotta. Some one will come upon poor Mike sooner or later, when not looking for him."