ISSN:0031-9228    

DOI:10.1063/1.3066560

出版商:AIP    

年代:1949

数据来源: AIP

摘要:

Long before Drake, in 1859, demonstrated that oil could be obtained by sinking wells, primitive man found it necessary to lubricate the axles of his carts and wagons to reduce friction and diminish wear. Lubricant taken from the axle of a chariot in a tomb sealed in about 1400 BC was analyzed and found to be beef or mutton tallow or a product of similar characteristics suitable for use in a warm climate. The first steam engines were lubricated with tallow, castor oil, and lard oil. While such animal and vegetable oils served their purpose in the primitive machine, they would be impractical in the engines of today, largely because of their inability to withstand the high temperatures involved. Oil in the crankcase of a heavy duty engine will reach one hundred and fifty degrees centigrade and the temperature at the upper piston ring grooves may exceed two hundred and fifty degrees centigrade. These high temperatures and the large quantities of air pulled through the crankcase ventilator make conditions especially favorable for oxidizing the oil which increases its viscosity, forms and precipitates sludge, and develops acidity. Fortunately chemical inhibitors have been found, small traces of which can be added to oils to reduce their susceptibility to oxidation.

ISSN:0031-9228    

DOI:10.1063/1.3066561

出版商:AIP    

年代:1949

数据来源: AIP

摘要:

Beryllium has unique and advantageous properties which make its use imperative in nuclear physics, nuclear reactor technology, metallurgy, and in industry. But there is danger in its use, for beryllium and its compounds have toxic properties and disease‐producing potentialities which have not been widely recognized.

ISSN:0031-9228    

DOI:10.1063/1.3066529

出版商:AIP    

年代:1949

数据来源: AIP

摘要:

Solid state physics is a field which has been in a somewhat unique position for about fifteen years. Although it probably will not continue to be unique very much longer, it may set a somewhat new pattern which other fields will follow. That pattern is the secondary exploitation by physicists of a field which physicists themselves have opened.

ISSN:0031-9228    

DOI:10.1063/1.3066530

出版商:AIP    

年代:1949

数据来源: AIP

摘要:

For maximally useful hearing it is important that bone‐conducted sounds—our own vocalizations and noises produced by chewing, swallowing, etc.—be minimized, while at the same time the ear remain maximally sensitive to airborne sounds.

ISSN:0031-9228    

DOI:10.1063/1.3066532

出版商:AIP    

年代:1949

数据来源: AIP

摘要:

It has been recognized for many years that the human eye, like most simple lenses, is afflicted to a certain extent with spherical aberration.

ISSN:0031-9228    

DOI:10.1063/1.3066536

出版商:AIP    

年代:1949

数据来源: AIP

摘要:

The most powerful and one of the most interesting known sources of high brightness and highest temperature, the high current carbon arc, is treated here both experimentally and theoretically.

ISSN:0031-9228    

DOI:10.1063/1.3066538

出版商:AIP    

年代:1949

数据来源: AIP

摘要:

The Seventh Pacific Science Congress which was held in New Zealand during February 1949 was the first after the war. The Congresses are mainly intended to unite scientists in fields with special interest in the Pacific Ocean. Thus, pure physics is not represented, but there are divisions of geophysics, geology, meteorology, and oceanography, in addition to other sections such as botany, zoology, public health, anthropology, and social science.

ISSN:0031-9228    

DOI:10.1063/1.3066540

出版商:AIP    

年代:1949

数据来源: AIP

摘要:

The present relationship between the professional physics societies and the newcomers to the field was considered by a group of some forty physicists, many of them heads of physics departments at colleges and universities in various parts of the country, who met at the National Academy of Sciences in Washington, D.C. on April 27. The meeting was concerned particularly with the possibility that some further organizational development geared to the special needs of students might in large measure eliminate certain problems now facing the graduate and undergraduate physicist.

ISSN:0031-9228    

DOI:10.1063/1.3066541

出版商:AIP    

年代:1949

数据来源: AIP

摘要:

Three California Institute of Technology scientists, Robert A. Millikan, Clark B. Millikan, and Louis G. Dunn, have received Presidential Medals for Merit awards, the highest given by the government for civilian participation in World War II.

ISSN:0031-9228    

DOI:10.1063/1.3066545

出版商:AIP    

年代:1949

数据来源: AIP