Volume 3, Issue 11, November 1932
Index of content:
3(1932); http://dx.doi.org/10.1063/1.1748882View Description Hide Description
A large Wilson cloud chamber operated by a synchronizing mechanism similar to that used by Blackett is described. It is shown how, by the use of mirrors, it is possible to take two photographs of the whole volume of the cloud chamber with a single lens, which are equivalent to photographs taken by two cameras at right angles. The design of such a camera is discussed in detail. The photographs are examined by replacing the developed film in the camera and using it as a projection apparatus. The two images can be combined on a suitably oriented plate as one image the same size as the original track. The method is thoroughly tested by photographing glass fibers and by range determinations. The reduction of the track lengths in the chamber to α‐particle ranges under standard conditions is discussed fully. It is shown that the interval between expansions must be made much longer than is customary if precision is to be attained in this reduction. The temperature in the chamber is carefully examined throughout the single cycle and repeated cycles to determine this interval and other thermal conditions of operation. The whole technique has been developed with the aim of utilizing as many tracks per expansion as possible for the purposes of range measurement.
3(1932); http://dx.doi.org/10.1063/1.1748884View Description Hide Description
In the course of studying various ferromagnetic rods, a group was found which showed a wide variation in the type and magnitude of the changes in length which occur when they were magnetized longitudinally. This collection included rods of iron,nickel,cobalt and alloys of cobalt‐iron. In a later paper it is proposed to correlate the final results in this paper with the mechanical hardness,elastic properties,hysteresis loss and change in resistance due to a magnetic field. In making the following study a new extensometer and recording camera were used. These are described in the following pages.
3(1932); http://dx.doi.org/10.1063/1.1748885View Description Hide Description
Dewar flasks obey Newton's law of cooling when the contents are adequately stirred. From cooling curves the water equivalent has been determined and the heat loss coefficient in calories per hour degree C difference has been found to be independent of the volume of contents between 50 percent and 90 percent capacity. For twin calorimetric purposes, flasks may be equalized by variation of the volume of contents as suggested by Hill, but it has been found that the best flasks are quite uniform and require but little compensation. The half‐pint flasks used have a heat loss of about 12 calories/hour degree C difference and water equivalent of about 36 cc.
3(1932); http://dx.doi.org/10.1063/1.1748888View Description Hide Description