perature of 60° F. An abridged table has accordingly been prepared, which has been approved by the American Petroleum Institute, the American Society for Testing Materials, the Bureau of Mines, and the Bureau of Standards. This table is not intended to replace the more complete table contained in Circular 154, which is regarded as official, but rather to supplement it, and especially to replace the various abridged tables and approximate correction factors heretofore employed in the oil industry. The eighteenth meeting of the National Conference on Weights and Measures, a body composed of officials from all parts of the country and devoted to the procurement of uniformity in weights and measures regulation, was held in May and was very successful. A code of specifications and tolerances for vehicle tanks was adopted, this superseding a tentative code adopted two years ago. Specifications and tolerances for taximeters were tentatively adopted, and a complete method of test for these instruments was developed. Tolerances for loaves of bread were also adopted. These are designed for use in the enforcement of existing standard-weight bread laws, and for incorporation in bills hereafter introduced involving this principle, which is making great headway throughout the country. The proper method of the sale of ice cream, a subject which has caused all those interested much concern in recent years, was given careful attention, and full opportunity was afforded to the manufacturer, the retailer, and the official to explain the matter in detail from their different viewpoints. A special committee will study he whole subject during the next year and report back a plan for consideration at the next meeting. The subject of the proper aparatus and methods for the test of heavy-capacity scales was conidered among many other timely subjects of importance. The field work in connection with the research on orifice meters for he measurement of natural gas in large quantities, as well as the omputations necessary to reduce the observed data to a comparable asis, have been completed, and the data show that a very wide range f conditions has been covered. The analysis of the results necesry to the formulation of conclusions from the research is now well nder way. A very simple scheme, involving on the average less than two eighings per weight and not requiring the use of substitution or ansposition methods of weighing, has been completed and will hortly be published. It is felt that this simplification will have he effect of stimulating many persons to calibrate their weights ho formerly have not done so, which will be followed by an crease in the general accuracy of laboratory weights and weighing. In addition to the test of watches, clocks, and chronometers, the reau cooperates with the Horological Institute of America in the xamination of applicants for certification as junior watchmakers, rtified watchmakers, and certified horologists. These examinaons consist of a written test and a practical demonstration of ility to repair a damaged watch. After repair by the candidate e watch is examined by a committee of expert watchmakers and tested by the bureau for performance as to time-keeping qualities. Service tests on a wide variety of stop-watches were carried out determine both their accuracy and durability. The results showed a wide range of performance. Socce of the watches failed after a aman. 1. inder of operation yles, consisting of starting, stopping, and return to zero. wille others continued to operate satisfactor through several thousand cycles. The best performance was 14.70 goes before fallure. ELECTRICITY Electrical measurements are theoretically based upon mechanics. forces and dimensions, but on account of the diffenty of fixing the units accurately the practical basis is an international agreement o electrical standards. It is now known that the international elec trical units are not exactly in agreement with the mechanical ones The bureau has in progress several projects which are intended to give better values for the electrical units and at the same time to simplify the process of checking up these values on a strictly correct basis. Fair progress has been made during the year on the appa ratus for determining the value of the ohm and the henry in absolute units, and experimental work on standard cells, by which the accepted value of the volt is maintained, has been revived after a lapse of several years. The extension of accurate measurements to keep pace with development in power transmission has taxed the resources of the bureau By refining the methods previously used, the calibration of voltage transformers is being carried up to 100,000 volts. An absolute ele trometer which will measure up to 350,000 volts is now ready for assembly. Accurate tests of resistance standards used for measure ment of current have been extended to 10,000 amperes on direct current, and tubular oil-cooled standards for tests of current tranformers at 5,000 amperes have been designed. Special attention has been given to the possible development of rubber compounds suitable for submarine cable insulation, and some have been found which are better than gutta-percha in electrici properties. To simulate deep-sea conditions apparatus has been installed for making electrical measurements on wires under hydrostatic pressures up to 10,000 pounds per square inch. Dry cells, storage batteries, and caustic soda primary batteries used for railway signaling have all received much attention during the year. The performance of all the important types of railway batteries has been determined, both at ordinary temperatures and a the freezing point, as a basis for specifications in preparation jointi by the American Railway Association, the battery manufacturers and the bureau. Effects of impurities in storage-battery electrolyte and the properties of several "patent" electrolytes have been the oughly studied. The results have been used both as a basis fo specifications for acid and in published warnings widely circulate to protect the public from fraud. Dry cells representing the pro uct of 23 manufacturers have been tested for the information of t manufacturers and of Government purchasing officers. During the year over 1,500,000 electric lamps purchased by the Government were inspected by the bureau; 3,194 samples were p through a life test to determine whether the lamps supplied were acceptable and to obtain data necessary for revision of the standar specifications. Sections of a circular on street lighting were put ished and tests on new street units for the District of Columbia vere made. Studies of automobile headlamps were actively coninued, and assistance on the headlight problem was given to conressional committees, the District director of traffic, and a number f States, especially Oregon, which has made all approvals of headamps subject to bureau tests. Methods of making more accurate measurements of frequency and means for getting these measurements into actual use have been he most important tasks in the field of radio communication. Acuracy was materially improved by using a simple harmonic amplier to step up from audio to radio frequencies, and by stepping down rom very high frequencies for which the wave lengths were easured directly on a parallel wire system. Standard frequency ignals covering the range from 125 to 6,000 kilocycles were transitted from the bureau and from Leland Stanford University at dvertised times, measurements on many stations were made at he bureau, frequency indicators were calibrated for high-grade tations, and lists of standard frequency stations were published eriodically. Improved frequency meters were developed, and a umber of quartz plate oscillators were prepared for use in interaboratory, and especially international, comparisons of frequency cales. A wide variety of cooperative investigations has been kept P, particularly observations of fading and other variations of sigals, and development of special equipment, such as direction nders, for other branches of the Government. Appreciable progess has been made toward the standardization of some radio aparatus, especially electron tubes. The survey of Government telephone service, carried on for the ast two years under the auspices of the Bureau of the Budget, has een continued and important additional economies have been acomplished both in the District of Columbia and in the field services. special assistance has been given to the Veterans' Bureau in choosng the telephone equipment for several hospitals, and to the Navy Deartment in testing out fire-control equipment. At the close of the ear the telephone engineering staff is largely engaged in preparaion of the technical phases of the Government's defense in a patent uit arising out of war use of telephone equipment and involving a Possible cost of several millions of dollars to the Government. A technologic paper has been prepared summarizing the bureau's onclusions on methods of testing to determine when damage is ccurring by electrolysis. This represents the results of many years' work in field surveys, and several months have been spent in disussions with representatives of the different utility interests inolved, in order to make this paper accord with their experience, in o far as is possible. A progress report covering the first sets of orrosion samples (iron pipe) dug up from different soils has been ssued through the American Foundrymen's Association. The samles have been carefully studied by many manufacturers and users of pipe. Since magnetic measurements seem to promise the only practicable nethod of testing steel rope in service, efforts have been continued o avoid the difficulties which have hitherto prevented the actual a wide range of performance. Some of the watches failed after small number of operation cycles, consisting of starting, stopping and return to zero, while others continued to operate satisfactori through several thousand cycles. The best performance was 14,7 cycles before failure. ELECTRICITY Electrical measurements are theoretically based upon mecha forces and dimensions, but on account of the difficulty of fixin units accurately the practical basis is an international agreeme electrical standards. It is now known that the internationa trical units are not exactly in agreement with the mechanica The bureau has in progress several projects which are inter give better values for the electrical units and at the same simplify the process of checking up these values on a strictl basis. Fair progress has been made during the year on t ratus for determining the value of the ohm and the henry lute units, and experimental work on standard cells, by accepted value of the volt is maintained, has been reviv lapse of several years. The extension of accurate measurements to keep pace wi ment in power transmission has taxed the resources of By refining the methods previously used, the calibration transformers is being carried up to 100,000 volts. An a trometer which will measure up to 350,000 volts is no assembly. Accurate tests of resistance standards used ment of current have been extended to 10,000 amperes o rent, and tubular oil-cooled standards for tests of cr formers at 5,000 amperes have been designed. Special attention has been given to the possible de rubber compounds suitable for submarine cable insulat have been found which are better than gutta-percha properties. To simulate deep-sea conditions apparatu stalled for making electrical measurements on wires static pressures up to 10,000 pounds per square inch. Dry cells, storage batteries, and caustic soda pri used for railway signaling have all received much at the year. The performance of all the important ty batteries has been determined, both at ordinary temp the freezing point, as a basis for specifications in pre by the American Railway Association, the battery and the bureau. Effects of impurities in storage-bat and the properties of several patent" electrolytes oughly studied. The results have been used both specifications for acid and in published warnings v to protect the public from fraud. Dry cells repres uct of 23 manufacturers have been tested for the in manufacturers and of Government purchasing office During the year over 1,500,000 electric lamps 1 Government were inspected by the bureau; 3,194 through a life test to determine whether the lam acceptable and to obtain data necessary for revisio specifications. Sections of a circular on street li w for adequate standardization ress involves not only e rate of tempera BUREAU OF STANDARDS ones. The mic 145 hed and tests on new street units for the District of Columbia e made. Studies of automobile headlamps were actively coned, and assistance on the headlight problem was given fo con ional committees, the District director of traffic, and a number ates, especially Oregon, which has made all approvals of head. subject to bureau tests. hods of making more accurate measurements of frequency and for getting these measurements into actual use have" beeti et important tasks in the field of radio comtounication. A as materially improved by using a simple harmonic ampli up from audio to radio frequencies, and by stepping down rety on a parallel wire system. Standard frequency frequencies for which the wave lengths were nag the range from 125 to 6,000 kiloegeles were trans e burean and from Leland Stanford University at Ses, measurements on many stations were made at ency indicators were calibrated for high grade tofandard frequency stations xera pooli hed (1. sromad frequency meters Sie weillators were prepared for we International. comparisons of frequency vore developed, and a * of fading and other variations of sig operative in zestigations har yeen kesk Decial equipment. The Government tandar lization of some pad o ap * and he fold stale and to the d gh een and sure y and ilable. eration nerican ers, that ss expensto.conhese limi arding the lem is still a developed. regards fire vior of strucal strength of of st .nowle in any on a sma classes |