This was the feature story of the July 27, 1912, issue of Scientific American—which, hang your head SURFER—is the nation's oldest continuously published magazine, and hats off to ironman editor Orson Munn, who helmed SA for sixty years, that's SIX-ZERO, starting in 1847. Other articles in this issue include "Heart-Stopping as a Profession," and "The Why and Wherefore of the Muffler." The author of "Artificial Surf Baths" is uncredited.

The International Hygiene Exposition of 1911, home to the Undosa (Latin for "abounding in waves") swimming tank, was held from May to October, in Germany, with over 30 nations participating. The Journal of the American Medical Association described the Expo as "representing the latest practical application of science to the maintenance of health and physical well-being." Popular Science added that the event had "succeeded in gently pressing the fruits of every known art, science and industry into the service of humanity."

Probably no feature of the International Hygiene Exposition held in Dresden last year attracted more general interest than the Undosa artificial surf bath. The receipts from the sale of bath tickets, and especially of spectators’ tickets, were unexpectedly large, amounting sometimes to $450 in a single day. As the cost of operation was only about $40 per day, it is evident that the artificial surf bath may be made a very profitable as well as a very beneficial institution.

The idea of generating waves in still water by alternately submerging and withdrawing solid bodies of appropriate form and dimension originated with Hofrat Hoeglaner of Munich, who in 1903 obtained a German patent for a wave-producing apparatus, which was subsequently patented in the United States and many other countries. The first experiment in the production of an artificial surf bath by this method was made in 1905 In a concrete basin built in Lake Stamberg.

The bath could be used only in summer, and. although it was very well patronized on clear hot days, it was evident that long periods of fine summer weather would be required in order to pay the operating expenses and provide for amortization and fair interest on the initial outlay.

It was left for the Dresden Hygienic Exposition to demonstrate that artificial surf baths can be made profitable by constructing them in such a manner that they can be used throughout the year in all sorts of weather. The directors of the Exposition had decided that the department of sport would not be complete without a large swimming bath in which swimming races could be conducted. The constructor of the bath. Herr Recknagel, suggested that it be provided with a removable roof, and also with apparatus for producing artificial surf. This plan was finally adopted after much discussion and with grave financial misgivings, and the result surpassed all expectations. During the five months of operation, the bath was visited by nearly half a million persons and earned about $30,000, which more than covered the cost of construction ($20,000), and the operating expenses (about $7,000). The cost of construction was diminished about one-half by the gratuitous contribution of many parts of the equipment by exhibitors, and the site cost nothing, but it appears probable that a similar enterprise would pay very well in normal conditions. The additional outlay for the wave-producing apparatus would not exceed $7,000.

The mechanical device by which the waves are produced is very simple in principle. It consists essentially of one or more hollow wedge-shaped bodies made of sheet iron, which are rhythmically immersed in and drawn out of the water by appropriate machinery. In situations in which the vertical elevation and depression of the wedges present difficulties the waves may be generated by oscillating vanes, but the operation is always so conducted that the water which rushes in to fill the void produced by the elevation of the wedge or the retraction of the vane passes the point of equilibrium and is heaped up by the return swing of the vane or the immersion of the wedge. The wave-forming action, therefore, is identical in principle with that of a stone thrown into a pond. If the stone falls close to the bank, so that the water can escape in only one direction, the height of the resultant waves is increased.

In the experimental plant in Lake Stamberg, the waves were generated by three immersion wedges arranged in a straight line, each of which was driven by a separate electric motor, in order to save space. Each motor was coupled directly to a flywheel. When the motor, running without load, had attained the proper speed of rotation, the motor shaft was connected by a worm drive with a horizontal shaft carrying a crank from the end of which the wedge-shaped plunger was suspended. In designing the artificial surf bath at the Dresden Exposition, steam was chosen as the motive power in order that the water of the bath and the air of the bathhouse might be heated by the exhaust steam. At first, the steam was supplied by the general powerhouse of the Exposition, about 1,000 feet distant, but subsequently a locomotive boiler of 100 horse-power was installed in the bathhouse.

The wave-generating plungers were suspended from cranks attached to a shaft extending across one end of the swimming tank, which was about 10' wide and 115' long. This shaft could be connected by belt wheels and clutches near its ends, with a countershaft at the middle of which was a wheel driven by a belt from the engine shaft. The gearing was constructed to immerse the plungers 18 times per minute when the engine was running at its normal rate of 125 revolutions per minute. The bottom of the basin was inclined in the usual manner, and the plungers were placed at its lower end, where the depth of water was about 7'. The waves generated at this end of the basin were more than 3 feet in height, and as they moved toward the other end and reached a point where the depth of water was less than their height they began to comb and break, and thus produced a very good imitation of the surf of a natural sea beach.

The arrangement of the plungers or vanes, and the character of the impulse impressed upon the water, can be varied in divers ways. Where space is limited, for example, a plunger could be attached directly to the piston rod of a vertical engine placed above it, as in one form of steam hammer. Plungers could be operated in the middle of a long basin so as to send waves toward both ends. The two parts of such a basin, divided by the machinery and a screen, could be used as separate baths for men and for women.

The height of the waves is conditioned by the volume of water displaced, and it can be varied within wide limits by varying either the travel of the plungers or the depth of water. For artificial basins, the best practical method consists in varying the travel and distributing several plungers across the deep end of the basin. With three plungers constructed to be operated separately, a great diversity of wave motion can be produced by using one plunger, two, or all three. It the three plungers. properly distributed, are operated together and synchronously, the whole basin is filled with regular waves of uniform height; while if even one plunger remains idle, the waves generated by the others spread into the calm water in front of it, and thus lose force and height as they approach the farther end. By accelerating or retarding individual plungers it is possible, as observation has shown, to produce a very complex wave pattern resembling that of the open sea.

Practically all of the conditions presented by a natural beach can be reproduced by doing away with the vertical wall at the shallow end of the basin and extending the Inclined door well beyond the waterline. The difficult art of swimming in rough water can be practised at one end of the basin, while at the other end bathers can enjoy the breakers, the outrunners of which furnish safe amusement for small children. All of these persons may derive benefit from the massage effected by the moving water.

"ARTIFICIAL SURF BATHS: A MINIATURE INDOOR OCEAN," SCIENTIFIC AMERICAN (1912)

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