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has. MERz himself has decisively recognized how much of the new work has been hidden in Challenger. ScuozT brings the relevant merits of BsxNNECKE to the fore and points out that the school 19 has referred to the North Atlantic Deep Current in an incomprehensible way; However, in the first edition of his Geography of the Atlantic Ocean, he does not take any notice of this, but instead uses his scheme of probable circulation between the surface and the deep ocean to explain the temperature conditions in the equatorial valleys, in line with LpNz's idea of the great oceanic yertical circulation. During the further elaboration of his important investigations carried out on board the "Deutschland", R'REhNECEE recognized that Antarctic water penetrates across the equator in z layers up to the northern tropical boundary, and North Atlantic water in between up to the Antarctic region. However, he has not yet detached himself from the conventional scheme of vertical circulation symmetrical to the equator. When he presented his results at the Leipzig Geographers' Conference, he still retained this scheme alongside his major horizontal movements, as he expressly confirmed to MzRz in his closing remarks. In that MER:' in the same session, on the basis of his studies of the observations of the older expeditions, for which he had only been able to use a few p r e v i o u s l y published "Germany" observations, contrasted BRxNxzcxz's picture of the exchange of water between the two hemispheres, which did not even contain the slightest hint of the Lzuz scheme advocated by Scuozz, he rejected the his dahi!a notion of the 3'ieìen water rising at the Equator with particular emphasis. There is no doubt that Mzsz not only helped the revolutionary new view to break through, but was also its independent originator. The new view has now also been incorporated into the second recently published edition of Scø onis Geographic des Atlantischen Ozeans, albeit without quel1enangał'e, riachdem 1hr Mznz Ă der ZeİtSGhr. d. Ges. f. Erdkunde i gae, p. i, has given the classical representation.
The clear view of the oceanic movements, which MERz had gained primarily through the study of the original works of the great expeditions of the seventies, provided him with the motive for the voyage of the "Meteor". The great scientific achievement of the German Atlantic Expedition was to make a revolutionary insight the basis for the study of the oceanic \'water\' circulation. MEn.z now wanted to try to grasp the spatial reality of the water turnover initially recognized for the abstraction of vertical circulation in a meri- dian plane.
The fact that Sch ozz is of such great scientific importance T h e f a c t t h a t h e w a s not able to put the expedition of the "Meteor" in the right light when he wrote his report for the Ann. d. Hydrograph. Hydrographie, is for me a great lack of accuracy.
ALBRECuv PEace.
The Michelson ezperi.ment, performed inside a free balloon.
The basis of Emszxlu's theory of relativity is the result of the so-called Michelson experiment, which states that the speed of light,

measured from the earth, is independent of its movement in space. I92ą hand, however, MicLER claimed t h a t there was an effect on Mount ĂVilson in the sense that the speed of light c h a n g e d in certain directions by up to Io km per second, in other words that an "aether wind" of this size existed. According to his first publications, this effect seemed to i n c r e a s e with altitude. It was reasonable to assume that if such an ether effect increasing with altitude existed, it w o u l d be particularly strong in the free atmosphere, so that an experiment in a free balloon should have a good chance of success.
Prof. A. Picc no brought this idea to fruition and, with the cooperation of the writer, a balloon ascent was undertaken on June 9-6. June 9-6 a balloon ascent was undertaken, the results of which are briefly reported below:
We used an interíerometer according to Mietec- son with multiple reflections (g mirrors) and an optical path of e8o cm. The line Ą358 of a mercury arc lamp served as the light source. The rotation of the apparatus is caused by the fact that the entire balloon is rotated by two electric motors suspended below the equator of the same with small aircraft propellers (* - 3 - rotations of the balloon per minute). This ensures complete symmetry. The interference stripes were not observed directly, but photographed on a film. This film was then measured in the laboratory, which significantly increases the accuracy, allows the speed of rotation of the balloon to be increased and avoids subjective errors.
The performance ïand on zo, June i9z6 in the evening lo o'clock with the J3allon Helvetia, which was kindly made available to us by the swiss. Aeroklub obligingly made it available to us (zzoo m* water stołí). The main measurements were taken between o and Ą o'clock at night at an altitude of 5oo m, latitude No ° ą 5 ' north and longitude 5 ° zo' east. Unfortunately, the temperature on this day was unusually high and instead of reaching temperatures below o °, for which t h e thermostat surrounding the interferometer was built, the temperature only dropped to -İ- y°. The resulting weak air vortices inside the apparatus caused interference line shifts, which reduced the accuracy of the measurements. As far as the mechanical stability of the balloon was concerned, however, this was fully achieved; for example, ballast release produced its noticeable interference line shift and the balloon fluctuations caused by this were at least too many times greater than those that can occur when the basket is kept still. Therefore, it is 1st certain that measurements with Mem 7ntezJerowefer itn Nreiòaffoa may be ficù mud.
In total, g6 usable balloon rotations were registered, which were divided into g groups. Each interval1 corresponding to one balloon revolution was divided into zo equal parts, for which the distance of the two sharpest interference stripes from the fixed point was determined using a dividing machine and microscope. Using the method of least squares, the sine curve with the prescribed period was calculated for each group which could best be reconciled with the observations. Its amplitude is proportional to the square of the "aether wind'', its phase gives the direction of the same. Vector averaging for the different groups finally yielded a most probable scattering distribution.

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b The N ature (knowledge)

Editor and responsible editor: Er.-5ng. e. Jj, DR. ARNOLD BERLINER, Berlin W 9. Published by Julius Springer in Bertin W g. - Printed by Spamersche Buchdruckerei m Leipzig.