make extraordinary instruments to whiz round, and point out places upon maps, and talk _so_ cleverly (but so incomprehensibly to you, my dears) about rusty coins and the backbones of fishes, and battered saucepans, which _they_ say are helmets. And then there are the nice stereoscopes to peep through, and the beautiful water-colour drawings and photographs to look at, and the old gentlemen are so quiet and so polite, and so different from the young men one meets in society, who either stammer and blush or are superciliously rude and put their hands in their trousers’ pockets. Yes, young ladies, the bald-headed old gentlemen, the careworn, long-haired, slovenly-looking men, are quiet and polite. They were, many of them, poor and humble once; but they have hewn out steps from the rock of knowledge, whereby they have mounted to that better fortune—European, Worldwide fame. That quiet man with gray hair, smiles when ministers press upon him a knighthood or a baronetcy: “_Cui bono?_” he says; “I would rather be a corresponding member of the Academy of Honolulu. When I am old and broke, and past work, you may give me enough for a little bread in my old days: I take it as a Right, not as a favour,” just as Turner the painter left in his will the simple direction that he was to be buried in the Cathedral Church of St. Paul.—“St. Paul’s is for the painters and the warriors, as Westminster Abbey is for the poets and statesmen; but I want not your honours and titles. Such as you have, you bestow on your lawyers and your lacqueys; but your captains are almost ashamed to take the decorations that are shared by footmen and backstairs cringers.” You have readily divined, I hope, why I have instructed the dexterous limner who illustrates these pages to select for his subject the scientific, rather than the literary, conversazione. The men of science do not obtrude their personalities upon the public. Their fame is known, their influence felt from London to Louisiana, but their portraits seldom meet the public eye. Those of General Tom Thumb or the Christy Minstrels would attract more crowds to the print-shop windows, and sell better. But, good lack! what a commotion there would be if the portraits of a series of _littérateurs_, in their habits as they live, appeared in “Twice Round the Clock!” I should be denounced, repudiated, vilified, abused, for the artist’s misdeeds. The great Mr. Polyphemus would crush me mercilessly beneath his iron heel; Grubstreet would (threaten to) kick me; Garbage would have me on the hip; O’Roarer smite me beneath the fifth rib; Leathers devise devices against me to make my existence intolerable; and Ethelred Guffoon castigate me terribly in his popular paper, “The Half-penny Cane.” No; let me deal only with the shadows; and those that the cobweb cap fits, e’en let them wear it. * * * * *