No abstract

Two genera of the Phallostethid fishes were anatomized using both the clearing and the dissection methods. While resembling Poecillids and agreeing with them in numerous anatomical features, these fish are true Acanthopterygians and apparently are correctly placed by Myers in the suborder Phallostethoidea erected for them in the order Percesoces. The two divergent types of priapia found in the group are readily derivable one from the other, corresponding bone for bone. The priapial bones can be homologized with the missing pelvic fins and girdle plus, perhaps, the post cleithrum and some of the pectoral pterygials. A comparison is made between the Phallostethid priapial skeleton and the highly modified girdle complex of the Polynemids.

The design and construction of the new NRC 2.1 metre cesium beam frequency standard, Cs V, are described and preliminary performance data are given. The standard is equipped with a cesium oven and detector at each end, and experiments show that it functions satisfactorily for both beam directions, with negligible interaction between the adjacent oven and detector. Operating characteristics for both beam directions are discussed in detail, and systematic errors for both modes of operation are outlined. Preliminary estimates indicate that the accuracy is between 1 and 2 x 10-ls. Comparisons with the NRC hydrogen masers show that a frequency stability of about 1 x is attainable within 120 sec.

Design and performance of two atomic hydrogen masers constructed a t the National Research Council, Ottawa, Canada, are discussed. Measurements are given of the relative stability of the two masers for periods from 10 sec to 3 weeks, and the maser frequencies related to that of the NRC long cesium beam frequency standard over a 41 day period. The latter measurements are related to other cesium frequency standards in the United States and Canada. The best stability for a single maser was found to be about 1 Y 10-14 for averaging periods of 1 h over a 24 h period.* To be published.

The convective heat transfer relations for atmospheric flow over sparsely vegetated areas are reviewed and compared to existing relations for flow in rough ducts. Experimental convection coefficients obtained at four desert sites are compared to the analytical relations. The experimental equipment for measuring the heat transfer convection coefficient between air and ground in a desert environment consists of two electrically heated plates positioned flush with the ground. Measurements of power dissipation and surface temperatures allow direct calculation of the convection coefficient. The experimental heat transfer results are correlated with micrometeorological models from which a soil roughness height is calculated. This roughness parameter is shown to characterize air flow near the soil surface, and may be significantly different from the roughness parameter ordinarily determined from velocity profiles. A simplified heat transfer correlation is presented for desert surfaces.