EEPORT OF THE SECRETARY. 13 



FOG-CLEARING INVESTIGATIONS. 



Aided by a grant of $2,000 from the Smithsonian Institution and a 

 grant from the Research Corporation, a committee of electrical engi- 

 neering experts, under the general direction of Mr. F. G. Cottrell, 

 continued during 1915 the investigations begun at San Francisco by 

 the University of California, in cooperation with the United States 

 Lighthouse Service, relative to the clearing of fog by means of elec- 

 trical precipitation. In a preliminary report read at the first meet- 

 ing of the committee. Prof. Ryan, of Stanford University, says: 



Science has established tlie fact that all dust and fog particles in the open 

 atmosphere are electrified and subject to dispersion or precipitation. It is ap- 

 parent, therefore, that a source of very high direct voltage, with facilities for 

 control and application, may be of inestimable value in certain quarters and 

 seasons for clearing fog away from a street, from along a passenger railway, from 

 around the landing stages of a ferry, or, possibly, about or in advance of a ship 

 under headway at sea. 



The clearing of fog differs from the treatment of smoke and fumes 

 in several respects, principally in that the smoke particles must be 

 actually deposited on the electrodes to bring about the desired effect, 

 whereas in treating fog it is only necessary to cause coalescence of 

 the minute particles into larger ones to give much greater transpar- 

 ency, even disregarding the more rapid settling of the larger drops. 

 However, other difficulties are to be expected in the problem of 

 clearing fog, such as the conditions arising from the continual 

 immersion in the wet atmosphere. What is chiefly needed for an 

 intelligent conception of the problem is actual first-hand experience 

 in handling these and other unusual conditions. 



The most striking features of the apparatus used in these experi- 

 ments are the Thordarson 350,000 to 1,000,000 volt transformers, 

 which I saw Avhile visiting the San Francisco Exposition. 



A great deal was learned during the year about the electrical 

 technique of the problem, and although days of suitable fog condi- 

 tions were extremely scarce, on the rare occasions of actual triAl very 

 perceptible clearing for a short distance around the high-tension 

 wires was obtained as the fog swept past. 



EXPLORATIONS OF ANCIENT MAYA CITIES IN GUATEMALA AND HONDURAS. 



Through the courtesy of the Carnegie Institution of Washington, 

 the Smithsonian Institution has been enabled to participate in some 

 very interesting explorations in Central America. Prof. W. H. 

 Holmes, head curator of anthropology in the National Museum, 

 gives the following general account of his work in that country : 



In February, 1916, owing to a generous grant of funds by the Smithsonian 

 Institution, the writer had the good fortune to become a member of the Car- 



