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er will not look upon it as in any sense discouraging. This study, un- dertaken on the basic premise that thrustmeters are precision trial in- struments only, is in a sense unfair both to the instruments described and to their designers, since it pre- supposes requirements which were probably never specified for the thrustmeters when they were built and performances which were never expected of them in service. The development of thrustmeters for shipboard use has, after all, en- gaged the attention of but relative- ly few people and those few have not had the time, the facilities, or the opportunity to push their lines of development to a satisfactory and final conclusion. It is to be expect- ed that a continuation of the effort put forth in the past few years to obtain ship trial data of a high de- gree of accuracy and reliability will be accompanied by the continued de- velopment of appliances for measur- ing propeller thrust and by the use of these instruments for gathering data on types of ships on which lit- tle authentic information of this kind is now available. 4 ¢ + Development in Ground Tackle é. for Naval Ships, by Rear Ad- miral E. S. Land, (CC), U.S.N., vice president. In this interesting paper, Admiral Land has given the society informa- tion on tests conducted by the navy department. He states that, It is not considered that they were nu- merous enough to justify radical de- partures from practices which have been in vogue for a number of years and proven satisfactory on a great variety of ships. However, suffi- cient data have been obtained to jus- tify some change in the ground tackle furnished vessels with the idea in view of saving an appreciable amount of weight and at the same time increasing the holding power of the ground tackle. With this end in view the size of chain designated for naval vessels now building is somewhat smaller than that which would have been furnished had they been designed several years ago; also, these ves- sels will be furnished anchors of the improved design. In the meantime the tests with which this paper deals will be continued until a sufficient amount of data on this subject is available to justify a further change in practice. Importance of Weight Saving Naturally, the bureau of construc- tion and repair has a technical and professional interest in the subject of ground tackle for naval vessels. In recent years this interest has been particularly enhanced on account of the weight limitations prescribed by naval treaties, of which the United States is signatory. The question of weight has always been one which has its home plate located in the bureau of construction and repair. The treaty limitations have made this question of far more vital importance than ever before. This in turn requires refinements of design in hull structures not other- wise considered of particular impor- tance. The ultimate object of a man-of- war is to carry an offensive weapon to the enemy. Every pound saved, either in hull design or machinery design, permits the utilization of this saving in the armament of a vessel. I should like to impress upon every member of this society the great importance of weight saving in our designs. This matter is not only of importance in our merchant ma- rine building, but also of vital im- portance in our naval building. 4 + ¢ Ventilation of Ships, by John » EF. Nichols, member. In this paper which deals with the important problem of ventilation, the author, who is chief engineer of the Newport News Shipbuilding & Dry Dock Co., includes the follow- ing, with reference to air condition- ing: A comparatively recent develop- ment in connection with ships’ ven- tilation has been the application of what for lack of a better term is called ‘‘air conditioning.’’ The re- sults have been so gratifying and so acceptable to the traveling public that air conditioning has become practically a necessity on any new passenger vessel, especially one de- signed to operate in the tropics, and its application is also being rapidly extended to existing vessels. Air conditioning has been defined as the treatment and control of air with respect to temperature, water vapor content, purity, distribution and motion. Properly speaking, air conditioning includes the warming and humidifying of the air when it Supply Airto Return Air from mole Dining Room Dining Room Outside Air Thermometer | Dampe'r Thermostat Control led Outside Air Dampers Fig. 1—Type of air conditioner in gen- eral use for larger spaces MARINE REvIEw—December, 1934 is too cool for comfort as well as cooling and dehumidifying the air when too warm, The first phase has been discussed under the section on “air heating’; the present discussion will be confined to the second phase, viz, air cooling. In summer weather we are un- comfortable both by reason of high air temperature and frequently (this is usually the case at sea) because the humidity is so high as to retard the evaporation of perspiration from the skin which is essential for com- fort. Consequently, the problem is both to cool and to dry the air. In order to reduce the amount of refrigeration that would otherwise be involved, some scheme of recircula- tion of the air is necessary and this in general restricts its application to spaces in which the doors and win- dows may be kept closed. Suecess- ful installations on new vessels have been made in this country to the first-class dining rooms of the MArrt- PposA and her two sister ships, to the \ Cooling Coil f f Floor \ Fig. 2—Air conditioning apparatus for individual staterooms ss main tourist dining rooms of the MANHATTAN and WASHINGTON and to the dining rooms of the CoLoMBIA and HaAtrti. In addition to the above, at the date of writing this paper, air condi- tioning has recently been added to the main dining rooms of the CALI- FORNIA, VIRGINIA and PENNSYLVANIA of the Panama Pacific line and to sev- eral yachts. The application to for- eign vessels has so far been very limited. While the application of air con- ditioning to date has been confined mainly to dining roms, the results are such that we may _ confidently look forward to its extension in the near future to other spaces, prob- ably at first to the de-luxe suites and later to other public rooms, though in these latter spaces special prob- lems will arise in connection with the necessity of keeping doors and windows closed. In the practical application of air conditioning the cooled air is intro- duced through specially formed out- lets near the top of the room. The endeavor is to lay down a blanket 13: