April 3.—It is really a very fine amusement to ascend the rope-ladder leading to the summit of the balloon-bag, and thence survey the surrounding world. From the car below you know the prospect is not so comprehensive—you can see little vertically. But seated here (where I write this) in the luxuriously-cushioned open piazza of the summit, one can see everything that is going on in all directions. Just now there is quite a crowd of balloons in sight, and they present a very animated appearance, while the air is resonant with the hum of so many millions of human voices. I have heard it asserted that when Yellow or (Pundit will have it) Violet, who is supposed to have been the first aeronaut, maintained the practicability of traversing the atmosphere in all directions, by merely ascending or descending until a favorable current was attained, he was scarcely hearkened to at all by his contemporaries, who looked upon him as merely an ingenious sort of madman, because the philosophers (?) of the day declared the thing impossible. Really now it does seem to me quite unaccountable how any thing so obviously feasible could have escaped the sagacity of the ancient savans. But in all ages the great obstacles to advancement in Art have been opposed by the so-called men of science. To be sure, our men of science are not quite so bigoted as those of old:—oh, I have something so queer to tell you on this topic. Do you know that it is not more than a thousand years ago since the metaphysicians consented to relieve the people of the singular fancy that there existed but two possible roads for the attainment of Truth! Believe it if you can! It appears that long, long ago, in the night of Time, there lived a Turkish philosopher (or Hindoo possibly) called Aries Tottle. This person introduced, or at all events propagated what was termed the deductive or a priori mode of investigation. He started with what he maintained to be axioms or “self-evident truths,” and thence proceeded “logically” to results. His greatest disciples were one Neuclid, and one Cant. Well, Aries Tottle flourished supreme until advent of one Hog, surnamed the “Ettrick Shepherd,” who preached an entirely different system, which he called the a posteriori or inductive. His plan referred altogether to Sensation. He proceeded by observing, analyzing, and classifying facts-instantiae naturae, as they were affectedly called—into general laws. Aries Tottle’s mode, in a word, was based on noumena; Hog’s on phenomena. Well, so great was the admiration excited by this latter system that, at its first introduction, Aries Tottle fell into disrepute; but finally he recovered ground and was permitted to divide the realm of Truth