Stand in the light of the window, Professor, said I.—­The Professor took up the desired position.—­You have white hairs, I said.—­Had ’em any time these twenty years, said the Professor.—­And the crow’s-foot,—­pes anserinus, rather.—­The Professor smiled, as I wanted him to, and the folds radiated like the ridges of a half-opened fan, from the outer corner of the eyes to the temples.—­And the calipers, said I.—­What are the calipers? he asked, curiously.—­Why, the parenthesis, said I.—­Parenthesis? said the Professor; what’s that?—­Why, look in the glass when you are disposed to laugh, and see if your mouth isn’t framed in a couple of crescent lines,—­so, my boy ( ).—­It’s all nonsense, said the Professor; just look at my biceps;—­and he began pulling off his coat to show me his arm.—­Be careful, said I; you can’t bear exposure to the air, at your time of life, as you could once.—­I will box with you, said the Professor, row with you, walk with you, ride with you, swim with you, or sit at table with you, for fifty dollars a side.—­Pluck survives stamina, I answered.

The Professor went off a little out of humor.  A few weeks afterwards he came in, looking very good-natured, and brought me a paper, which I have here, and from which I shall read you some portions, if you don’t object.  He had been thinking the matter over, he said,—­had read Cicero.  “De Senectute,” and made up his mind to meet old age half way.  These were some of his reflections that he had written down; so here you have

THE PROFESSOR’S PAPER.

There is no doubt when old age begins.  The human body is a furnace which keeps in blast three-score years and ten, more or less.  It burns about three hundred pounds of carbon a year, (besides other fuel,) when in fair working order, according to a great chemist’s estimate.  When the fire slackens, life declines; when it goes out, we are dead.

It has been shown by some noted French experimenters, that the amount of combustion increases up to about the thirtieth year, remains stationary to about forty-five, and then diminishes.  This last is the point where old age starts from.  The great fact of physical life is the perpetual commerce with the elements, and the fire is the measure of it.

About this time of life, if food is plenty where you live,—­for that, you know, regulates matrimony,—­you may be expecting to find yourself a grandfather some fine morning; a kind of domestic felicity that gives one a cool shiver of delight to think of, as among the not remotely possible events.

I don’t mind much those slipshod lines Dr. Johnson wrote to Thrale, telling her about life’s declining from thirty-five; the furnace is in full blast for ten years longer, as I have said.  The Romans came very near the mark; their age of enlistment reached from seventeen to forty-six years.

What is the use of fighting against the seasons, or the tides, or the movements of the planetary bodies, or this ebb in the wave of life that flows through us?  We are old fellows from the moment the fire begins to go out.  Let us always behave like gentlemen when we are introduced to new acquaintance.