Page:Popular Science Monthly Volume 23.djvu/297

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staff-cells proceeding from the hypodermis, with which those nerves are connected; and, third, of a supplementary apparatus, composed of cavities or cones filled with a serous fluid, which may be regarded as out-foldings of the epidermis. The organs appear to be most highly developed, as would naturally be supposed, in those insects which appear to use the sense of smell in seeking for food. The greatest number of smelling cavities and cones are found among wasps and bees, the honey-bee having fourteen or fifteen thousand cavities and about two hundred cones in each antenna, the leaf-wasp a smaller number. The flesh-and-dirt flies have from sixty to a hundred and fifty organs of smell, while the flies that live on plants have only five or six cavities to each feeler.


Photographing the Corona.—Professor Huggins announces that he has succeeded in photographing the solar corona without the assistance of an eclipse. It having been shown by Professor Schuster's observations of the last eclipse that the coronal fight as a whole is very strong in the region of the spectrum extending from about G to H, he conceived that by making exclusive use of this part of the spectrum, while enjoying the best possible conditions of exposure and concentration, it might be possible to take a photograph of the kind sought. He found a commercial violet (pot) glass which effected the separation required, and using this—and a potassic permanganate solution in his later experiments—with a reflecting telescope, and gelatine plates, he obtained twenty successful photographs between June and the 28th of September of last year. Captain Abney, whose experiments during the last eclipse have made him a competent judge, declares the photographs as trustworthy as any that were taken then. Professor Huggins believes that there is little doubt that under the most favorable conditions the corona may by his method be successfully photographed from day to day with a definiteness which would allow of the study of the changes which are doubtless always going on in it. By an adjustment of the times of exposure, the inner or the outer corona could be obtained as might be desired.


Cram Examinations.—"Hot-house Education" is the title of a pamphlet recently published in England, on the absurdity of the examinations in vogue there, which are systematically prepared for by cramming. Dr. Crichton Browne is authority for the statement that, by submitting boys of twelve or thirteen to the examinations, "we may be able to select those of the quickest wits, and those most susceptible of cram; but we should certainly not bring to the front those of the greatest grasp of intellect and force of character," and that to institute such examinations at such an age seems to be offering a premium on precocity. In the examinations of older candidates, tests are often exacted of a kind which an examiner who has been quoted by Mr. Froude described as setting a paper "for which Macaulay might possibly get full marks." A case is cited by Mr. Digby, the author of the pamphlet we have referred to, of an examiner who had to appeal to the Geographical Society for the answer to a problem which he had set to candidates, but could not for the time being solve himself. Another instance is that of an examiner for the army who gave out as a subject of composition, "A Visit by Sir Roger de Coverley and the 'Spectator' to Lord's Cricket-Ground." Such cases might, perhaps, be met by fixing the rule that those who make the examinations should be required to pass them.


The Right to Rest.—The London "Spectator" calls for the establishment of a new rule of etiquette, that a man who announces that he is seeking rest shall be let alone. In the hurry and strain of modern intellectual life, a necessity has arisen for periodic rest. "Overwork" is now recognized by physicians as a specific cause of disease, and a few of them are making the effects of over-cerebration, under a hundred names, a distinct specialty. The incomes of several first-class doctors in London are derived almost entirely from men whose brains are overworn, and whose nerves are so "overstrung," or "understrung," or "gone to pieces," or are "so excited," that they can neither sleep, nor work, nor remain quiet. These specialists have become abnormally discerning, and "can tell almost at a glance where anxiety has been the cause of disease,