Page:Popular Science Monthly Volume 22.djvu/435

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the brain with an earnestness which it is safe to call extreme. He assails with controversial ardor the logic of Dr. Hammond's views, and endeavors to show that they are inconsistent with themselves, and are not supported by the facts whence they are drawn, or by the authors from whose works Dr. Hammond has endeavored to substantiate particular points of his theory.

The Solution of the Pyramid Problem, or Pyramid Discoveries, with a New Theory as to their Ancient Use. By Robert Ballard, of Queensland. New York: John Wiley & Sons. 1882. Pp. 109.

Mr. Ballard is not the first who has advanced a theory as to the purpose for which the pyramids were built, nor even the first to conjecture that they were of use in resurveying the land after the annual inundations of the Nile. "Built by scientific men, well versed in geometry, these great stone monuments are so suited in shape for the purposes of land-surveying, that the practical engineer or surveyor must, after consideration, admit that they may have been built mainly for this purpose." The author also thinks that he has discovered the unit of measure used in their construction, and to which he gives the name of Royal Babylonian cubit. This cubit he makes equal to 20·22 British inches, and as there are 77,760,000 royal Babylonian cubits to the polar circumference of the earth, the cubit represents the 160 of a second. This he claims is the most perfect ancient measure yet discovered. It is a perfect, natural, and convenient measure which fits the plan of the pyramids and fits the circumference of the earth. The author also states that the pyramid of Cheops is situated on one acute angle of a right-angled triangle, and the pyramid called Mycerinus is on the other acute angle, the other two sides of which run respectively east and south from these pyramids. The sides of this triangle are respectively 3, 4, and 5. The pyramids of Cheops and Cephren are situated on the acute angles of a still more remarkable triangle, the sides of which are to each other as 20, 21, and 29. Many other curious facts are mentioned regarding the dimensions, position, and slope of the pyramids, and a description of the method in which the author supposes them to have been used as the "theodolites of the Egyptians." Many of the obelisks, he thinks, were probably marks on pyramid lines of survey, and the pyramid may have been a development of the obelisk for this purpose.

A Guide to Collodio-Etching. By Benjamin Hartley. Illustrated by the author. New York: The Industrial Publication Company. Pp. 48, with Six Plates.

This little work is for the benefit of amateurs, who feel the need of some simple and inexpensive method of duplicating their sketches and studies for the benefit of their friends. The various methods by lithography, photography, and the photo-engraving of pen-and-ink drawings which have been suggested by different persons, have been found by the author to be inconvenient, expensive, and troublesome. He describes, as more nearly realizing than any other one the conditions required by the amateur, a process for drawing the sketch with a needle upon the glass plate, as prepared by the photographer for the camera, and printing from the etching as an ordinary photograph is printed. He undertakes to give all the practical information necessary on the subject, so that persons who know nothing about photography may be able to carry into effect all the details of his system.

United States Commission of Fish and Fisheries. Report of the Commissioner for 1879. Washington: Government Printing-Office. Pp. 846.

The report embraces an inquiry into the history and statistics of food-fishes, and a summary of what has been accomplished in the matter of their propagation in the waters of the United States. Among the collateral subjects of attention by the commission have been an investigation into the chemical composition of fish under the varying circumstances of age, sex, and the condition of the reproductive apparatus; researches into the temperature of fishes, experiments in the production of cold for the preservation of fish, and the preparation of a series of casts in plaster and papier-maché of the larger species. The pole flounder, which was discovered off the coast of New England in 1877, proves to be one