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Welsbach burner with mantle, fitted to screw into the base of a Bunsen burner. Over the mantle in the place of the ordinary glass chimney a sheet iron chimney somewhat shorter is used. In this, at the proper distance from the bottom, a circular aperture is cut about 1⁄2 inch in diameter and across this is soldered a fine wire for indicator. The light with hood then is in no way connected with galvanometer or scale so that in the adjustment of either the galvanometer is not disturbed.

A SIMPLE APPARATUS FOR PARALLEL FORCES

D. F. ROSS, YPSILANTI

This piece of apparatus is designed to overcome an element of error in the experiment of the composition of parallel forces. When the two draw-scales, or coiled springs, used to represent the two forces,

are attached to fixed supports there is but a single position for the point of application of their resultant such that the bar will assume a horizontal position; and when the bar assumes an inclined position, the forces are no longer acting parallel with each other, and this inclination is considerable, if the springs are quite sensitive, the nearer this point approaches either of the other forces.

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The accompanying figure illustrates a means of overcoming this difficulty, and needs but little explanation to make its action clear. The spring "S" is fastened to a scale which can be raised or lowered as the occasion requires, and held in position by means of the setscrew, "K." "C" is a back view of this sliding scale, showing the two brass plates which project beyond the edges and slide in grooves in the uprights, shown in "A," thus holding it in position and at the same time admitting of a free movement. A scale not shown in the figure, on each upright, enables the student to readily bring the bar into a horizontal position.

The piece is simple, inexpensive, and gives good results.

APPARATUS FOR DEMONSTRATING LAWS OF LIQUID

PRESSURE

H. C. KRENERICK, BERWYN, ILL.

With diagram and print, the apparatus will need but a brief description. The tubes, A and B, are a meter or more in length. Tube B is of two parts, so that the upper part can be replaced by tubes of different diameters. The liquid used is a very dilute solution of potas

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sium permanganate. In the print two manometers are shown; one is the open, and the other, the closed form.

The laws which, I believe, can be satisfactorily demonstrated are: That the pressure is proportional to depth, or water-head; that it is proportional to the density of the liquid; and that it is independent of the shape of the containing vessel. The apparatus serves also to show the use of the open and closed manometers.

To demonstrate the first law, use but one tube, clamping off the other by means of the clamp C. By forcing air into the bottle through

the rubber tube T, the liquid can be raised to any desired height in A. When the clamp in T is closed, the column is held, and the readings can then be taken. By varying the height of the column, a series of readings can be obtained. Knowing the use of the open manometer, the pressures can be obtained, and the relation between depth and pressure determined.

To show the effect of a variation in density, fill the tube B with different solutions, the densities of which have been previously determined. The tube is then connected, and the column lowered to a definite or constant height. The readings of the manometer for the different solutions show the expected relation between pressure and density. Care must be taken to lower the liquid until the entire column is of the solution.

The independence of the pressure from the shape of the vessel is easily shown by replacing the upper part of B with other tubes of different diameters, especially with one in which several bulbs have been blown. It is well to experiment also with the tube inclined to the vertical. I believe the most satisfactory and interesting application of the apparatus is the demonstration of this hydrostatic paradox. Students after studying the text are sometimes inclined to disbelieve the principle in all cases. I usually disconnect the larger tube and have some student, by blowing through the tube T, force the liquid as high as he possibly can in the one tube. When the second and larger tube is also in communication with the bottle, he is very much surprised in finding that the two columns can be raised as easily as the

one.

The fact that in most text-books the order of topics is such that manometers and related matter are presented somewhat later than the principles of liquid pressure may cause the application of the manometer to be an objection to the use of the apparatus. If such a piece can be obtained, this objection can be prevented and the apparatus very much simplified by connecting directly to the bottle a small pressure gauge in place of the manometer.

BIOLOGICAL CONFERENCE AND SCIENCE TEACHING

LABORATORY WORK AND ITS RELATION TO FIELD WORK

DR. J. G. NEEDHAM, LAKE FOREST COLLEGE, ILL.

The adjustment of field work and laboratory work in any course in biology should proceed upon the assumption that these are complemental and not antagonistic. Their method does not differ necessarily, but only the conditions under which they are carried on. Either may be static or dynamic according to the purpose for which it is used. Both are necessary for the rounding out of most biological inquiries. Both are means, not ends, and should be used accordingly as they serve the pedagogical purpose of the work in hand.

The laboratory has certain great advantages for any work which may be carried on within it. Some of these arise out of our psychological and physical limitations. The laboratory has a roof and a floor and is usable in all weathers. It has walls which shut out distractions. It has tables and chairs whereon we may dispose our members and our implements; and it has conveniences for assembling around us while we work more apparatus and reagents than would be manageable otherwise. Furthermore, it has means of control of light and heat and other forces, useful in experimentation, which cannot be had outside its walls.

These advantages are so great that we take our work into the laboratory whenever possible. There are, however, certain phases of ecology, distribution studies, and all studies of life in relation to environment in extenso, that may not be done within the laboratory, just as there are studies, like histology, which can make no progress apart from laboratory equipment. However, most biological, even most, ecological studies are furthered by the concurrent and complemental use of both field and laboratory; for each with inevitably raise questions best answered by the other.

Life in action is studied in the field; mechanisms and adjustments are worked out in the laboratory. In general, the field gives us our broad conceptions, the laboratory our nearer and clearer views.

LABORATORY WORK IN

BIOLOGY-ITS NATURE, CON

DUCT AND VALUE*

LOUIS MURBACH, CENTRAL HIGH SCHOOL, DETROIT.

Biology was introduced into high schools mostly at the instance of colleges when it was established in the higher institutions. First it was allowed, then required for college entrance and was naturally

shaped after college work. Recently it is being held that biology should be taught in secondary schools in such a way as to be a part of their scheme of giving a more liberal education—to better realize his position in nature to the youth who cannot hope to go to college.

There is probably as much difference in the nature of laboratory work in biology as there are teachers teaching it, although at first thought there might not seem to be much difference so long as it is laboratory work. Being directed to find certain things in a specimen, and how they "look," and what is their significance is one kind of laboratory work. It is still current in colleges and does less harm there than in the high school. It is a great way in advance of the older text-book method. The pupil becomes a verifier; if he ever attains to more he may thank some innate genius or change of environment.

To begin with, then, specimens are to be placed in the hands of all pupils. Mere observations and descriptions of specimens is not a very enlivening work, but may be made more so by the introduction of experiments that bear on the nature of the specimens studied. It is assumed that both the observational work and experiments will be followed by reading and discussion. Study many specimens, at least in the way of comparison, but require only one or two to be drawn and described. So in experiments, there should be as many as can be done, though only the principal one need be written out. Drawing the apparatus used in experiments is time put in that might be better employed. Nearly half the course should be laboratory work, strictly considered. This would leave the other half to be divided between ecological, or field work, and book work, including the discussion or recitation.

Nearly half the time of any study, especially in the lower grade of the high school, should be for the training of the observation, manual dexterity, and the judgment. To further this end the work should be carefully graded and carefully worded. Only those things that are beyond the pupil's comprehension should be told him and then in such way that he will understand that it is not his own idea; and, what is of no less importance, he should be early taught how to express or to show in his record, what is his own observation or inference and what he has from the book or from his teacher.

* * *

The laboratory books that give ready made observations and conclusions for secondary schools are still numerous. This alone would be sufficient reason for every teacher making his own laboratory book. *** Most of the biological work laid out for second year high school pupils should be simpler. The ideal way would be to have so few students that we might give each student such individual attention. With our large numbers we are compelled to adopt more formal methods, and our pupils are reduced to one level which, I fear, is much below what the best in the class could do. Even if we have such simple and explicit directions that the majority can work

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