PROJECTION.

The actual projection method is as follows: The lantern is operated and the microscopic position varied so as to get the maximum illumination. The screen is set up as directed, perpendicular to the beam of light, and on the same level. The slide is prepared by placing a drop of the colloidal solution on an ordinary microscopic slide, and covering with a cover glass to eliminate evaporation. (The heat from the lantern may be cut off by a water cell placed between the condensing lenses. This will eliminate any danger of over-heating the objectives of the microscope.) The microscope is adjusted in the usual fashion, until a clear image is secured. If the foregoing directions are observed, the projection of the Brownian Movements becomes as easy as any type of microscopic projection.

It is hardly necessary to add that the foregoing combination of apparatus may be used for any type of high or low microscopic projections. It should prove of great value to teachers

of science.

BARBER'S STANDARDIZED SCIENCE TEST FOR GENERAL SCIENCE.

It takes nowadays a pretty well educated person in science to be able to successfully teach the subject of general science, because it embodies so many different sciences if the work is to be done efficiently. These little tests that Mr. Barber has prepared for general science teachers cover, in a remarkable degree, all phases of the work. Any general science teacher who has the interest of his work at heart should prepare himself with a set of these tests. They may be had from A. B. Barber, Clayton, New Mexico.

POSITION OF FEET IN FLIGHT IN CERTAIN BIRDS.

Here are several apparent "rules" in bird life that have interested me for some time, and they are passed on to the readers of The Condor for what they are worth.

1. All water birds in flight extend the feet behind.

2. All web-footed birds, with short tails, spread the toes in flight, the membranes apparently acting as an elevator or rudder. This group includes the murres, murrelets, auks, and puffins.

3. All perching birds in flight fold the legs forward under the feathers. All the short-tailed, web-footed birds that I have had under close observation, when getting under way do spread the toes, placing them side by side to form a wide flat surface, which is no doubt useful in flight. By the tine these birds may have attained their regular speed, possibly the toes are relaxed, but they are then as a rule too far distant for accurate observation. I am not so certain that loons follow this rule. Grebes, which are lobe-footed, spread the lobe flat out in rising from the water and, I think, close the toes after attaining full speed.-[The Condor.

A METHOD OF SCIENCE PROCEDURE.

BY E. S. OBOURN,

Mansfield High School, Mansfield, Pa.

As a teacher of science in secondary schools the writer has had very good results with this method which has been thoroughly tried out. It is being passed on at face value with the hope that some one may gain some usable points from it. In planning and using this device, effort has been made to conform as closely as possible to the fundamental psychological principles underlying the learning processes. This article is written from the standpoint of physics but has been used with very slight modifications in chemistry classes.

The physics classes with which the writer has had experience have always been large. The teaching of such a class has usually resolved itself primarily into a problem of accommodation. With facilities for an average class, classes of from forty to fifty have confronted me. To do as efficient teaching as possible under such conditions, the following procedure has been used.

At the beginning of the year the large class is divided into two groups which will be designated as A and B for convenience sake. When the groups have been organized, usually about the second meeting of the class, a preliminary science test is given which embodies questions from every possible source of everyday science. The motive of this test is to determine just how much elementary scientific data the pupil has at his disposal. This test serves also as a basis for pupil classification and guide for the measuring of results obtained.

The work of the year is divided into closely related units or principles, each unit occupying as much time as its importance demands. Physics is arranged on the school program in such a manner that the two sections come at consecutive periods of the day. These periods are from forty to fifty minutes in length. The time of the unit is divided as follows:

The first day is a day of assignment. The work is laid out for them, assignments made in the pupils' reference text and in the reference texts from the science library. The required reading is at least two of the assignments made. The work is carefully assigned and troublesome points made clear by an introductory discussion. If a demonstration is possible it is used as a means to arouse and stimulate interest in the problem at hand. Near the close of the period the assignment of a laboratory exercise,

bearing directly upon the solution of the problem, is made. An effort is made to arouse interest by assigning the exercise in the form of a question; for example, instead of assigning the conventional experiment, "To find the Specific Gravity of A Liquid," such a question as this is placed on the board, "How May a Hydrometer be Constructed? What are some of its practical uses?" Such assignments tend to arouse a spirit of wonder in the pupil and a desire to accomplish. The above is given to group A during the first hour and to group B during the second. hour.

On the second day of the unit, group A assembles in the laboratory for the solution of the problem assigned on the previous day. Before the students are allowed to go to work the instructor goes over the laboratory directions carefully and points out any parts from which a difficulty may appear to rise. During the progress of the work, the instructor visits the several working groups, quizzing various ones on fundamental points either of construction, theory or operation. At the close of the hour, time is taken to sum up the data obtained and to draw certain definite conclusions. Group B assembles on the third day of the unit for the same laboratory work that group A had on the second day.

The fourth day of the unit is given over to the regular meeting of the groups at their assigned periods. This meeting takes the form of a class conference rather than a formal recitation. Questions arising from the assigned reading and from the work in the laboratory are brought up and discussed. The instructor keeps in the background as much as possible and attempts to direct the questions and problems which come up in such a manner as to secure the most thorough discussion. These class conferences tend to keep the pupils awake every moment of the period and are found to go a long way toward stimulating interest.

If the fourth day of the unit is not sufficient to clear all problems and complete the discussions, more time is given. The length of the unit depends largely upon the importance of the problem at hand. In this procedure one of the elements which has proven successful is a very elastic program. On the days. when problems and points of difficulty are discussed, if the answer can better be found by the pupil he is sent into the laboratory to solve his own problem.

At very frequent intervals a test is given to measure the

abilities which have been developed. These tests are given in several different forms. For example the biographical side of physics is tested by a simple matching test. Laws are readily tested by true-false tests. The range of information may be tested by completion tests, matching tests or association tests. Problem solving ability may be tested by a simple test which includes fundamental problems.

The teacher may relieve himself of considerable burden if the pupils are allowed to score the tests. The students exchange papers, the correct answers to the several questions are rapidly read and the score determined. Before the papers are handed back to the owners, the instructor asks each student for the score on the paper which he holds. These are placed on the blackboard in several columns which represent the distribution of the class scores. When this has been done, the papers are handed back to their owners. In this way the test serves not alone as a test but also as a stimulant to the low pupils. There is, however, a point which is to be guarded against, lest the pupils who stand high be content to rest on their attainment.

Whenever the work in physics is of such a nature as to make project work possible and advisable, the above procedure is varied to meet conditions. For example; in the study of pneumatic appliances the instructor posts on the bulletin board a list of projects and each student is permitted to select the one nearest his interest. The students selecting the same project are then organized and a group leader selected. The work is planned with the help of the instructor and each group proceeds to work out the problems of the project, whether it be the construction of a hydraulic elevator or measuring the suction of a vacuum sweeper. A number of reference text assignments are made, which are required readings. The readings are so selected that every phase of every project is covered. These serve to give the pupil a background when the work of the different groups is presented to the rest of the class.

A definite length of time is given over to the study of the projects and the solution of the problems arising from them. At the conclusion of this time, each group is given about one period to bring its work before the class and make a definite report upon it. Time is given for the class discussion of each project. Each student of every group is required to write up a report of every project in which ten fundamental questions bearing on the project and submitted by the members of the

group which have selected that project, must be answered. These reports are then handed to the members of the respective groups and are looked over by them. If they are satisfactory they are brought to the instructor for approval and credit. If they are unsatisfactory they are turned back for correction.

Besides the work on pneumatic appliances, many parts of the work in physics may be treated in this manner. Parts of Heat, especially the study of modes of heat transfer and heat engines, lend themselves aptly to the project method. Certain parts of Electricity and Light may also be taught in this way.

In the use of this plan of procedure, the several units which go to make up the year's work are bound together by lectures and talks in which an attempt is made to point out to the student the broader governing laws and principles of physics. For example a lecture on the work principle serves to bind the Mechanics of Solids to the Mechanics of Liquids. A lecture on energy and its forms binds Mechanics with Heat and Electricity. A lecture on wave motion binds Heat, Light and Electricity. Frequent use of the stereopticon makes these lectures more interesting and lasting.

PRINTING DOUBLE-WEIGHT PAPERS.

The continuously greater use which is being made of double-weight papers of practically postcard substance for portrait-photographs, inserted without mounting in the popular folders, calls for somewhat greater care in printing, says The British Journal. The curl of a fair-sized piece of such paper may easily be such that proper contact over all parts of the negative is not obtained in a printing-frame fitted with the customary rather weak springs, or in a printing-box if hand-application of the pressure-back chances to be done in a careless manner. With some printing-boxes uniform pressure of the back calls for correct manipulation of the handle, and when a thick paper is being used it is quite possible to have faulty contact over part of the negative. In many cases this liability may be readily remedied by thickening the pressure-pad by fixing a stout piece of felt to it, or by laying a piece of felt upon the paper after inserting a fresh piece of the latter. Of course, a precaution such as this will be taken by the experienced printer, especially if he has been accustomed to handle carbontissue, the pronounced curl of which calls for the frames of extra solid construction provided with strong springs fitted to hinged cross-bars. The fact that exposure of papers is often placed in the hands of comparatively unskilled assistants is no doubt responsible for defects of definition in prints which have been submitted to us with the suggestion that the lens was at fault. That such was not the case should have been evident from the fact that the unsharpness occurred in different parts of the subject from the same negative.-[Photo-Era.