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occasion to depart widely from his present performance. One example—his description of the Edison steam-dynamo—will suffice to show the accuracy and lucidity of the definitions of this remarkable dictionary:

Dynamo-Machine, Edison's Large. This is a machine directly in the piston of an engine, and is composed of four electro-magnets, the poles, and with pipes for the circulation of air. The machine and Porter & Allen's engines are all built on a cast-iron base, the whole weighing about twenty-two tons. The field-magnets are of cast-iron, and the resistance varies between one and two ohms. The magnets are wound with No. 10 wire, Brown and Sharp gauge. The enormous pole-pieces are of cast-iron, and Edison maintains the necessity for using such pole pieces. The armature consists of a steel shaft six inches in diameter. Mr. Edison and many other electricians claim that a low-resistance machine is the best form. Edison's latest dynamo-machine has a resistance of one two-thousandth of an ohm. Ninety-seven per cent of the electricity out of the machine is available.

The pamphlet on the storage of electricity has the advantage of the dictionary in that Mr. Greer's work consists in little more than editorial revision. The pamphlet contains a good part of Professor Sylvanus Thompson's excellent lecture before the Society of Arts on the storage of electricity, the advantage of the storage-battery as set forth in the circular of the Brush-Swan Company, and the statement of the value of the Faure battery given in the circular issued by the American company controlling this apparatus, together with descriptions of various other storage-batteries, some taken from different technical journals, and some written by Mr. Greer.

On Prehistoric Trephining and Cranial Amulets. By Robert Fletcher, Acting Assistant-Surgeon, United States Army. Washington: Government Printing-Office. Pp. 32, with Nine Plates.

Though published as one of the documents of the Powell Geographical and Geological Survey, the matter of this monograph is more European than American, but is susceptible of an American application. The author has aimed, starting from Broca's summary of the subject in 1877, to collect the accounts of discoveries of examples of trephining and cranial amulets scattered through the journals of anthropology, not only on account of their interest in themselves, but also for the sake of the illustration and guidance they may afford in American research. Numerous curious instances of the practice of trephining and the fabrication of amulets are brought to light, and the conclusions are adduced that the large number of perforated crania, exhibiting cicatrized edges, establishes the existence of a custom of trephining; that the operation was performed on both sexes? and generally at an early age; that it seems (from analogy) to have been for the relief of disease of brain, injury of skull, epilepsy, or convulsions; that it was probably performed by scraping, possibly by a scries of punctures; that posthumous trephining consisted in removing fragments of the skull of a person who had undergone surgical trephining, in which each fragment was probably to form an amulet to protect from the same disease or injury for relief of which the operation had been performed; and that the evidence so far confines the custom to neolithic man on the Continent of Europe.

The Naval Use of the Dynamo-Machine and Electric Light. By Lieutenant J. B. Murdock, U. S. Navy, U. S. Naval Institute, Annapolis, Md. Pp. 44.

In this paper, Lieutenant Murdock has collected and compiled from the current scientific literature of the day such information bearing on the subject as will enable one to reach a more exact comprehension of the field open for the electric light in modern naval warfare. The applicability of the various machines and apparatuses that have been introduced is discussed, and the modifications are considered that may be necessary to adapt them to use on shipboard.

"The Sociologist." A Monthly Journal devoted to the Increase of Knowledge of the Natural Laws that control Human Happiness. Adair Creek, Knox County, East Tennessee: A. Chavannes & Co. Pp. 10. Fifty cents a year.

The publication of this journal has been undertaken for the love of the cause. The editor has sought for a paper especially devoted to the study of sociology, and, not finding it, has decided to furnish one. Profit is not the especial object of the publishers, but to create a means of communication and a means of exchange of thoughts and opinions.