380 SCHOOL SCIENCE AND MATHEMATICS

Place the neck of such a balloon over the faucet and run inabout ^quart^of water. Support the ball of water on the ex-tended palm of the left hand and give it a horizontal accelera-tion by a pull on the neck of the balloon with the right hand.This causes it to take on an elongated shape in the direction ofthe pull. It will be stretched not only on the side of the pull,but due to the inertia of the water within, it will bulge on theopposite side.The attraction of the moon and sun acts in much the same

way on the earth. But the earth is constantly rotating to theeast causing the tidal bulges to travel round the earth to thewest. The earth not being a fluid or even viscious, but quiterigid, yields only partially to the tidal strains, with the resultthat tides are produced in the oceans relative to the solid part.

If a smaller amount of water, say a .cupful, be placed in therubber balloon, and then tied to a cord, and whirled about ina circle in a vertical plane, the elongation of the balloon in thedirection of the cord will be quite pronounced. This illustratesthe permanent tides produced in the moon by the attractionof the earth, the rate of rotation of the moon equaling its aver-age rate of revolution about the earth.

In this experimental illustration of the cause of the tidesit will be borne in mind that the stretched rubber tends to keepthe water in an approximately spherical form, whereas therotating world is kept in an approximately spherical form bythe mutual gravitation of its parts.

IMPROVISED SCIENCE APPARATUSBY ALFRED POWERS

University of Oregon, Eugene.Home-made equipment, crude but satisfactory physics in-

struments are emphasized at the University of Oregon to theextent that instruction is offered in making them. This instruc-tion is given in a course known as physics technics and is espe-cially designed for those who would teach sciences in high school.The course consists of the making of simple instruments that

require no great amount of machinery in the manufacture.Soldering and glass-blowing are taken up. Vessels and tubesare made of glass. Resistances for use in electrical work aremade by stringing wires on boards. Wheatstone bridges andmeter sticks are manufactured. Galvanometers are made bywinding coils of wire around boxes in which compass needles

EUCLID DRAMATIZED 381

are placed. In addition, many instruments are devised to assistin the study of light and sound, as well as in mechanical ex-periments.One of the most notable pieces of work was the making of a

pair of optical benches by an undergraduate. The set is usedin the university laboratory for the study of lenses in connectionwith experiments in light.The purpose of the course in physics mechanics is to teach

the construction of apparatus rather than its use. Since thework is intended for those who expect to teach physics in highschools it is highly important that the prospective teachers beable to carry on laboratory work with many instruments oftheir own making. With this end in view, the majority of thosewho have taken the course have kept the apparatus which theyhave made. This practice of construction has also been followedby those doing research work.

It is the plan at present, according to Dr. W. P. Boynton,head of the physics department, to have a machine shop designedfor instrument making. In connection with the shop therewould be an expert in manufacturing apparatus. In additionto making instruments for the physics department, the man incharge of the shop would also make apparatus for other sciencedepartments of the university.

EUCLID DRAMATIZED.By MARGARET GRAFF,

S.outh Philadelphia High School for Girls.Whoever thought of dramatizing Euclid? This was done recently by

girls of the South Philadelphia High School. The girls in two of thewriter’s classes in geometry asked if they might not dramatize and presentbefore the school some of the stories of early mathematicians told them inthe course of their regular work in order that they might show the pioneerspirit in mathematics. They were told that they might do so if theywished and if they would work out their plans themselves. This they didfaithfully, except at the end the head of the English department super-vised a number of rehearsals and the head of the art department in-spected the costumes. Their classroom teacher referred them to Ball’sHistory of Mathematics, also Cajori’s History and Smith’s Teaching ofGeometry. They found other material for themselves in various places.The performance started with a five minute account of the life of Thales.

Immediately afterwards, the curtain was drawn, revealing King Amasisseated upon his throne with two slaves back of him holding gorgeous fansand other attendants standing about. The king lamented that no onehad been able to measure the height of the pyramids and promised to re-ward richly any one who could do this. One of the court then told theking that there was in their midst a Greek scholar who could do this bya simple method. Amasis commanded that the Greek be summoned.