“Very true,” said Ellen, suddenly recollecting the necessity of accounting for her own appearance abroad at that unseasonable hour; “I know many who think the earth has a pleasanter look in the night, than when seen by the brightest sunshine.”

“Ah! Their organs of sight must be too convex! But the man who wishes to study the active habits of the feline race, or the variety, albinos, must, indeed, be stirring at this hour. I dare say, there are men who prefer even looking at objects by twilight, for the simple reason, that they see better at that time of the day.”

“And is this the cause why you are so much abroad in the night?”

“I am abroad at night, my good girl, because the earth in its diurnal revolutions leaves the light of the sun but half the time on any given meridian, and because what I have to do cannot be performed in twelve or fifteen consecutive hours. Now have I been off two days from the family, in seach of a plant, that is known to exist on the tributaries of La Platte, without seeing even a blade of grass that is not already enumerated and classed.”

“You have been unfortunate, Doctor, but—”

“Unfortunate!” echoed the little man, sideling nigher to his companion, and producing his tablets with an air in which exultation struggled, strangely, with an affectation of self-abasement. “No, no, Ellen, I am any thing but unfortunate. Unless, indeed, a man may be so called, whose fortune is made, whose fame may be said to be established for ever, whose name will go down to posterity with that of Buffon—Buffon! a mere compiler: one who flourishes on the foundation of other men’s labours. No; pari passu with Solander, who bought his knowledge with pain and privations!”

“Have you discovered a mine, Doctor Bat?”

“More than a mine; a treasure coined, and fit for instant use, girl.—Listen! I was making the angle necessary to intersect the line of your uncle’s march, after my fruitless search, when I heard sounds like the explosion produced by fire arms—”

“Yes,” exclaimed Ellen, eagerly, “we had an alarm—”

“And thought I was lost,” continued the man of science, too much bent on his own ideas, to understand her interruption. “Little danger of that! I made my own base, knew the length of the perpendicular by calculation, and to draw the hypothenuse had nothing to do but to work my angle. I supposed the guns were fired for my benefit, and changed my course for the sounds—not that I think the sense more accurate, or even as accurate as a mathematical calculation, but I feared that some of the children might need my services.”

“They are all happily—”

“Listen,” interrupted the other, already forgetting his affected anxiety for his patients, in the greater importance of the present subject. “I had crossed a large tract of prairie—for sound is conveyed far where there is little obstruction—when I heard the trampling of feet, as if bisons were beating the earth. Then I caught a distant view of a herd of quadrupeds, rushing up and down the swells—animals, which would have still remained unknown and undescribed, had it not been for a most felicitous accident! One, and he a noble specimen of the whole! was running a little apart from the rest. The herd made an inclination in my direction, in which the solitary animal coincided, and this brought him within fifty yards of the spot where I stood. I profited by the opportunity, and by the aid of steel and taper, I wrote his description on the spot. I would have given a thousand dollars, Ellen, for a single shot from the rifle of one of the boys!”