NOVEMBEE 2, 1906.] 



SCIENCE. 



551 



thrown out by Skaptar Jokull would equal 

 in quantity that which could be heaped up 

 to a thickness of some seven or eight feet 

 over almost the entire area which in Cali- 

 fornia lies between the line of displacement 

 in the recent earthquake and the Pacific 

 Ocean; while the discharge from Temboro, 

 if properly estimated, would have filled in 

 a mile-wide canal to a depth of ten feet 

 over a length of 15,000 miles. One may 

 well stand appalled by these figures, but 

 they have as yet produced little impression 

 upon the geologist to whom the major 

 lesson of vulcanology is taught by Vesuvius 

 or Etna. 



The general conclusions arrived at in this 

 paper are: 



1. A broad interrelationship exists be- 

 tween volcanic and seismic phenomena gen- 

 erally ; 



2. Interrelated manifestations of volcanic 

 and seismic activity may extend over dis- 

 tances, as measured on the surface of the 

 globe, of hundreds or even thousands of 

 miles ; 



3. 'Tectonic' earthquakes, so-called, are 

 only doubtfully to be distinguished from 

 earthquakes of volcanic association, or those 

 that have been brought about as the result 

 of deep-seated strain ; 



4. The slipping, upheaval and torsion of 

 terranes as accompaniments of earthquake 

 action are the resultants of impacts or jars 

 already delivered to the earth's crust, and 

 are not the cause of such jars ; 



5. Earthquake and volcanic disturbances 

 seem to be the expression of one common in- 

 terior telluric strain or condition, and this 

 condition may in some or many cases be 

 clearly associated with a pronounced mag- 

 netic or electro-magnetic quality of the 

 planet ; 



6. There would appear to be a marked 

 synchronism or close following of major dis- 

 turbances, whether volcanic or seismic, at 



distantly removed points of the earth's sur- 

 face at certain periods. 



Angelo Heilprin, 



SCIENTIFIC BOOKS. 



The Adjustment of Observations ty the 

 Method of Least Squares with Applications 

 to Geodetic Worlc. By Thomas Wallace 

 Wright, M.A., C.E., professor emeritug. 

 Union College, formerly assistant engineer, 

 Survey of the Northern and Northwestern 

 Lakes. With the cooperation of John Fill- 

 more Hayford, C.E., Chief of the Com- 

 puting Division and Inspector of Geodetic 

 Work, U. S. Coast and Geodetic Survey. 

 Second edition. Pp. ix + 298. New York, 

 D. Van Nostrand Company. 1906. 

 The average man of science generally ex- 

 hibits a remarkable lack of ordinary commoi> 

 sense when dealing with the method of least 

 squares and its conclusions. Inferences are 

 drawn from a series of observations, and de- 

 ductions made from the size of the probable 

 error which at times seem so totally at vari- 

 ance with the truth that much fault has been 

 found with the method. In theory, the prob- 

 able error is based on the assumption that the 

 errors are all accidental, that is, are just as 

 likely to be positive as negative, and that 

 there are a large number of observations, 

 whereas in practise, the formula for finding 

 the probable error is often applied to a very 

 few observations not freed from their sys- 

 tematic or constant errors. A consequence of 

 this is that a degree of precision is shown 

 which is much greater than the observations 

 themselves really warrant, and the probable 

 error, therefore, does not seem an accurate 

 measure of the error committed. 



There are other scientists who believe that 

 a least square reduction is a great correction 

 of evils, and that by its means very satisfac- 

 tory results may be derived from an indifferent 

 set of observations. While poor observing 

 will give nothing but poor conclusions, it 

 seems to be quite a favorite trick of the com- 

 puter, nevertheless, to introduce new un- 

 knowns into the observation equations with the 

 hope of more correctly solving them. When 



