e set up
for life, or at least as long as the patent lasted, and it would be well
to be sure to arrange it to last through his natural life.

Indeed, he had gone so far as to make his invention. It had been
suggested by their trouble with a key, in their late moving to their new
house. He had studied the matter over a great deal. He looked it up in
the Encyclopaedia, and had spent a day or two in the Public Library, in
reading about Chubb's Lock and other patent locks.

But his plan was more simple. It was this: that all keys should be made
alike!

He wondered it had not been thought of before; but so it was, Solomon
John said, with all inventions, with Christopher Columbus, and
everybody. Nobody knew the invention till it was invented, and then it
looked very simple. With Agamemnon's plan you need have but one key,
that should fit everything! It should be a medium-sized key, not too
large to carry. It ought to answer for a house door, but you might open
a portmanteau with it. How much less danger there would be of losing
one's keys if there were only one to lose!

Mrs. Peterkin thought it would be inconvenient if their father were out,
and she wanted to open the jam-closet for the little boys. But Agamemnon
explained that he did not mean there should be but one key in the
family, or in a town,--you might have as many as you pleased, only they
should all be alike.

Elizabeth Eliza felt it would be a great convenience,--they could keep
the front door always locked, yet she could open it with the key of her
upper drawer; that she was sure to have with her. And Mrs. Peterkin felt
it might be a convenience if they had one on each story, so that they
need not go up and down for it.

Mr. Peterkin studied all the papers and advertisements, to decide about
the lawyer whom they should consult, and at last, one morning, they went
into town to visit a patent-agent.

Elizabeth Eliza took the occasion to make a call upon the lady from
Philadelphia, but she came back hurriedly to her mother.

"I have had a delightful call," she said; "but--perhaps I was wrong--I
could not help, in conversation, speaking of Agamemnon's proposed
patent. I ought not to have mentioned it, as such things are kept
profound secrets; they say women always do tell things; I suppose that
is the reason."

"But where is the harm?" asked Mrs. Peterkin. "I'm sure you can trust
the lady from Philadelphia."

Elizabeth Eliza then explained that the lady