Page:The New International Encyclopædia 1st ed. v. 11.djvu/716

LABORATORY. waste water by open troughs to the vertical earthenware main pipes, so avoiding leadwork altogether. The system of flues for ventilation of the hoods must be carried over the whole building. This system may be connected with a lofty chimney, or with a rotary fan. Electricity is usually supplied, for scientific purposes, from accumulator batteries.

Each student working in a room has a locked desk for his own use. The desks are usually supplied with gas, water, vacuum-pumps, draught-closets, apparatus, and reagents, so as to reduce to a minimum the cases in which it is necessary for the student to leave his desk. Space is economized in most laboratories, in the rooms set apart for beginners, by dividing the space under each desk into two independent closets, so that two students may use the same desk at different hours or on different days. In the larger laboratories much special apparatus is found, such as a machine for producing liquid air, grinding mills driven by power, working models of chemical industrial works, and apparatus for treating materials on an industrial scale.

The technical laboratories maintained by industrial establishments may be simply for analytical work, in which case they may be modeled after the rooms for quantitative analysis in the teaching laboratories; but in cases where experimental work is carried on, the plan is quite different. Power must be supplied more freely, facilities provided for handling larger quantities of material, and liberal space left free to set up working models of apparatus on a large scale. See section on Engineering Laboratories.

. Rooms specially equipped for physical experimentation were not provided until long after well-organized chemical laboratories were in use. Such early experimenters as Boyle, Newton, and Franklin made use of their own living apartments for their experiments, and it was not until well into the nineteenth century that professors of physics obtained separate rooms in which they could carry on work with due convenience. The next step was for these professors to admit students to their own laboratories, and to direct their research. At Heidelberg the first physical laboratory was opened in 1846, two rooms being devoted to instruction in practical physics. The laboratory at the University of Glasgow where original research was carried on by students under the direction of Lord Kelvin was also one of the earliest of these Laboratories. In France, in spite of the brilliant work done in private laboratories in the first half of the nineteenth century, the facilities for systematic work by students were hardly as ample as in Germany, but by 1868 it was realized that additional accommodations for students and research laboratories for professors and skilled investigators were essential. One result of this movement was the foundation, in the Sorbonne in Paris, of a physical laboratory, of which Jamin was made director, and which has been celebrated not only for his researches, but also for those of Lippman. This laboratory was placed under the direction of the faculty of science in 1894 and was then remodeled. King's College, London, also adopted regular laboratory training as part of its work in physics about this time, and three rooms in its building were used as a laboratory. The first building in England specially designed for

the study of experimental physics was constructed at Oxford, under plans of Prof. Robert B. Clifton. This was followed by the Cavendish laboratory at Cambridge, built in 1874 by Prof. James Clerk-Maxwell, who incorporated in it many of Professor Clifton's ideas. In the United States the progress was naturally slower than in Europe, but it is asserted that the first institution to make laboratory physics a part of its regular educational work was the Massachusetts Institute of Technology, in Boston. The systematic work begun at the Massachusetts Institute of Technology in practical physics furnished an example which was soon followed by other American colleges, including Cornell and Harvard, and even by many high schools, and so rapid was the progress made that in 1886 Harvard required experimental work in physics in its entrance examinations.

In elementary laboratory work in physics, the apparatus is simple and the results demanded are qualitative rather than quantitative. A laboratory for this purpose would be merely one or more rooms provided with suitable tables. The simple apparatus used should, where possible, be constructed by the student himself, the use of tools for the making, adjusting, and repair of apparatus forming not the least valuable part of the training. The ordinary manipulation of glass tubes, and the use of the more common wood-working tools, as well as of a few implements for cutting and shaping metal, must be learned by the student at an early stage.

The entrance requirements for the colleges have set the standard for the physical work to be done in preparatory schools. No elaborate instruments are required for such courses, and it is considered better practice to have the student work as accurately as possible with somewhat crude apparatus. In the college laboratory the equipment is of a much higher grade, and should be as extensive as the means of the institution will permit. The student here begins to work quantitatively, and accuracy of observation and measurement is the prime essential of his work. The usual method of instruction is to have an elementary course which covers the essential features of physics. That is, a student will begin with the ordinary measurements of length, mass, and time. He will perform quantitative experiments in sound, heat, light, and electricity. There must be at his disposal measures of length and micrometers of various forms which will enable him to determine length or thickness to one-hundredth of a millimeter, or even less. He will also have analytical balances for determining the mass of substances with an accuracy of the one-hundredth of a milligram, and such other instruments as accurately calibrated thermometers, standards of electrical resistance carefully determined, and optical apparatus in which the graduated circles and other parts used for measurement are of high precision. As the construction of this apparatus involves considerable mechanical skill, it is, of course, impossible for the student to make it; but its test and calibration is one of his first tasks. He is taught the necessity of correcting his observations and looking for and compensating for such causes of error as can be detected, and, in short, to attain as great accuracy as the apparatus he uses is capable of.

For elementary laboratories no extensive and peculiar structural features are required in the