nto it just on that account. He
says that perhaps I would forget to take care of my own safety, but he
is sure I will never fail to look after this little pet. For instance,
when I was learning to fly three years ago (and I don't consider that I
really know how to do it yet) they tried to din it into me that I must
always keep the tail of my machine a little higher than the nose, in
case the engine should go dead when I wasn't expecting it."

"What would happen then?" asked Bill, deeply interested.

"Well, if the aeroplane is correctly balanced with the tail a little
higher than the nose it will be ready for a glide if the engine goes
dead, and on the other hand it is apt to lose headway, and go down tail
first. And that, you know," added Ernest, laughing, "is often very
uncomfortable for the occupants of the car."

"I should say so!" agreed Bill.

"Chaps make such a mistake trying to build their own cars," said Ernest.
"More accidents come from that than people realize. While the war was
going on, no one had time to tinker at building, but now half the chaps
I know are studying up and attempting to make aeroplanes for themselves.

"It just can't be done. For instance, every piece of wood used in a
machine must be tested with the greatest care. A chap can't do that
himself. Every piece of wire used has got to be stretched in a machine
specially invented for the purpose. For instance, to find the breaking
strain of a piece of wire, a piece fifteen inches long is placed between
the jaws of a standard testing machine, so that a length of ten inches
of the wire is clear between the two ends. What they call the 'load' is
then put on by means of a handle at the rate of speed of about one inch
a minute. You can't do this yourself, and by the time you have sent your
wire, or have taken it where the test can be applied, and have also had
the test made on the twist of your wire, and all the woodwork, you will
have a machine that will cost more than one made by skilled workmen.
There is another test too that is very necessary. That is for your wing
fabric. It ought all to be soaked in salt water. If the fabric has been
varnished, the salt will soften it. Then dry the sample in the sun and
if it neither stretches nor shrinks, you will know that it is all right,
and you will feel safe about using it."

"I took in all I could learn, without actually going up, at the Aviation
field at Sill," said Bill. "I will get my chance some