Page:Popular Science Monthly Volume 20.djvu/299

Rh distance at which the signals are to be seen. At present three sizes are used, corresponding with distances of two and a half, eight, and ten and a half miles. The medium size measures about twenty by thirty inches, and weighs, with the telescope, less than twenty pounds. If the apparatus is to be used at night, artificial illumination will be needed; a petroleum-lamp with a reflector, or, for greater distances, two lamps, will be enough. To use the apparatus, the album must be fixed on its tripod at such an angle that the reflection from the silver shall be brightest, and shall reach the spot with which communication is to be had. A plate which is all silvered, and which appears in the distance as a bright point, is exposed as a signal of warning: the operator at the other post answers with an identical signal that he is ready. The letters composing the telegram are then exhibited one after the other, and the words are separated by showing the wholly silvered plate or plain spot. If any signal is to be repeated, as in the case of double letters or the repetition of a figure, it is hid for a moment by a black leaf and shown again. The operator at the other station receives the dispatch with the aid of his telescope, distinguishing the letters and spelling the words as they come, and writing them, or having them written, down. The image produced by these huge characters, seen at a distance through the glass, corresponds with sufficient exactness with that produced by the same characters when read in a book or a newspaper. In the experiments that have been made, dispatches of twenty words have been transmitted in five minutes. Speed may be gained by using single conventional characters for the more common words. Secrecy may be secured by so fencing in the album as to prevent the diffusion of its reflection, and limit the field of its visibility to the other station, or by employing a cipher.

Ancient Aboriginal Houses.—Judge Henderson, of Illinois, discussing the character of the houses of the ancient inhabitants of the Mississippi Valley, said that it was a mistake to regard the "cone-like cabin"—which is really only a temporary hunting-hut or abode of a tribe in a nomadic condition—as the typical wigwams of the aborigines at the beginning of the historic period. Such houses were not found in the villages of the sedentary tribes, but these lived in large houses, each accommodating a number of families belonging to the same gens. These long houses were made with framework, and covered with such material as the country afforded—bark in the East, mats made from the leaves of the cat-tail in the prairies of the West—and were divided into sections by skins, sheets of bark, or mats hung up at intervals, and had a hallway in the middle, extending the full length of the house. One family occupied each of these sections, and a fire built in the doorway of every second partition served for two families. In the South, the houses were of sticks plastered with mud, and sometimes covered with mats, while the roof was covered with mats or thatched with straw or canes. The absence of any traces of ruins or of foundations shows that the houses of the ancient inhabitants of the land could not have been of stone, or massive structures of wood; and they could not have been of adobe, for that would not have withstood our winters. Professor Morgan's theory that the houses were pueblos, built