The expensiveness of apparatus has long been felt as a formidable difficulty in the effort to make scientific education popular and practicable. There is double hindrance here; the instruments of experiment are so costly that they cannot be procured for common use, and because of this expensiveness they have to be kept in careful charge, so that ordinary pupils cannot use them, and must content themselves merely to look on and see others work. But what is wanted indispensably is, that all the students shall be themselves put to work; shall be set to making experiments, and observing and proving things for themselves. The obstacles to such a course have hitherto been so great and so general that pupils have had but little chance to cultivate manipulation; and but few schools, in fact, have been able to procure the instruments requisite for demonstration on the part of the teacher. To remedy these difficulties and point out not only how scientific apparatus for physical experiments can be cheaply made, but how much the pupil can do to help himself in the matter, Prof. Mayer, of the Stevens Polytechnic Institute, has undertaken a series of little books, of which the first is now published. His choice of a subject to begin with is most fortunate. The phenomena of light are at once familiar and attractive, are always available, and admit of appliances for illustration of the most simplified and inexpensive character. We give ample illustrations of this in another article of the Monthly, from which the reader will see how much can be done in the way of careful experimental work for the illustration of the principles of optics, with but a small outlay of money and but little trouble.
The authors say in the preface: "It is believed that this book will occupy a place hitherto unfilled in scientific literature. It is specially prepared for the boy or girl student and for the teacher who has no apparatus, and who wishes his pupils to become experimenters, strict reasoners, and exact observers. Nearly all the experiments described are new, and all have been thoroughly tested. The materials employed are of the cheapest and most common description, and all the experiments may be performed at an expense of less than fifteen dollars. The apparatus is at the same time suitable for regular and daily use in both the home and school, and with care should last for years."
It is proper to add, in explanation of the joint authorship of the work, that Prof. Mayer has been long busy in inventing simple and cheap apparatus to help teachers and pupils in the art of experimenting; but, being greatly occupied with his professional duties, he made an arrangement with Mr. Charles Barnard to assist him in preparing his results for the press. All the contrivances and inventions for illustrating experiments belong to Prof. Mayer; Mr. Barnard has attended to the detail in the execution of the book, while Prof. Mayer has maintained a close supervision of the work.
In this report Prof. Baird gives the results thus far obtained in the inquiry into the decrease of food-fishes, and the efforts to protect and propagate them in American waters. The work in which the commission is engaged is an important one; it has been pushed with vigor, and with results which upon the whole are encouraging. The extent to which fish can be made to contribute to the food-supply is not generally appreciated. It is not alone the fisheries of the coasts and the Great Lakes that may be made to have value, but every mile of river and creek, and every pond and even ditch, may, with proper management, be made to contribute toward supporting a stock of fish. They manage these things better in China, and have carried pisciculture to an extent unknown among Western nations.
Many of the indigenous game-fish decline to adapt themselves to the changed