Alaska sentinel., 1907-02-28
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unfailingly foretells changes in the weather. This stone was found in Fin land many years ago by an explorer, and has since been watched by scien- lists with great interest. It presents a white, mottled appearance In sun shine, gradually turning from gray to black as rainstorm approaches The stone Is composed of clay, hitter and rock salt. In dry weather the salt in the stone Is prominent, but when the air Is filled with moisture the salt ab- sorbs the moisture and turns black, thus forming the barometer.
 At Strasburg, Germany, a dental clinic has been opened at the university for the treatment of school children. Hither all the school children are sent, in order, by their teachers. Each child Is quickly examined, as many as eighty children being dealt with In an hour, and nearly 300 a day, by single doc tor. Teaching goes hand In hand with treatment. The doctor tells the child how to use tooth brush, sees that he uses one, and sends him home to prac- tice with 1t. The movement Is spread ing. In Wiesbaden and Mulhausen school dental clinics are to be erected.
 Among the natural curlosities dis covered by the Belgian exploring expe- dition In the country lying between the basins of the Congo and the Nile was wild flg-tree-Figuier du dlable- which, having by the chance of the winds had Its birth on the sum- nit of an enormous rock of granite, and finding no nourishment for its ex- banding roots near by, sent one long root ln search of soil down the face of the rock until 1t reached the rich earth at the bottom. There 1t buried itself In the ground, and thus estab- llshed chain of life for the depend ent plant above.
 Fluid resins or oils from several diff ferent trees are extensively used In tho Philippines as varnishes One of them, called oil of supa, Is a pale yellow liquid when fresh. but 1t becomes dark and yiscious after contact with the air. Spread in a thin layer, 1t dries slowly and forms hard varnish. It is also capable of being burned In lamp. Another natural varnish Is ba- lao, also called oil of apitong. It Is white when fresh. but darkens after exposure, and makes very tough var nish. OH of panao Is third variety, inferior to the others In It's drying properties. Chemical analysis has shown that all these wood oils consist entirely of hydrocarbons known as sesquiterpenes.
 Many of the scientific journals in Europe lately have given attention to curious discovery reported to the Paris Academy of Sciences by Profes- sor Bouchard. This discovery is that under the action of the X-rays gray hair, on the head and face of a patient treated for lupus, gradually assumed Its natural color, and retained 1t with surprising tenacity. But only the hair directly reached by the rays was thus affected, and 1t Is pointed out that 1t would be dangerous to employ such method to restore the color of a per sons hair. The fact Is regarded as interesting in Itself, but should not be accepted as basis for the opera tions and claims of quacks. Professor Bouchard said that he did not wish to base any practical conclusions upon It.
 Dr. Guthnlck of the Royal Observa- tory at Berlin has recently announced the result of his photometric studies of six of the principal satellites of Sat urn. He confirms the previous conclu- sions of other observers that several, and perhaps all, of these satellites be- have like our own moon In keeping al- ways the same side toward the planet round which they reyolve. In regard to the satellite named Tethys, he of fers an interesting hypothesis to ac- count for Its very marked changes of luminosity. His idea Is that Tethys possesses the form of long elllpsoid the two principal axes of which are to one another In the ratio of five to two. It will be remembered that sim liar suggestion has been made concern ing the shape of the asteroid Eros, which likewise exhibits great variations of light, according to Its position In its orbit about the sun.
 All the ingenuity that has been em. ployed in the past few years in the in- vention of submarine boats would be wasted but for the means that have been found to bestow upon the sub merged vessel or upon those who navi- gate 1t, the ability to see what Is go- ing on upon the surface of the water. These means are simple in principle, as they depend only upon the reflection and conduction of light, but almost every nation has Its own methods of supplying "eyes" to Its submarine war boats, and the details are kept more or less secret Universally, the appa.
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