January 28, 1910] 



SCIENCE 



157 



new evasion that pain does not hurt — finds them 

 as unnecessary as the parallel postulate. 



13. For purposes of navigation, in checking the 

 longitude, Mr. Wetherill proposes that the moon 

 be observed in meridian altitude, and with the 

 known latitude, the declination be interpolated in 

 the " Nautical Almanac " for G. T. Where the 

 change of declination is rapid per minute of time 

 a good check can be made without the complica- 

 tion to the seaman of the calculation of the lunar 

 distance. 



14. Mr. Clough's study of meteorological and 

 solar variations of short period discloses cyclical 

 variations in the length of the period similar to 

 those shown in 1904 to be characteristic of the 

 11-year and 36-year periods. The 3J-year varia- 

 tion in the frequency of prominence and other 

 solar phenomena, and the barometric pressure over 

 Iceland and the Azores, ranges in length from 

 about 2J years in 1875 to 3i to 4 years in 1860 

 and 1893, showing a 36-year variation in the 

 length of the period. The mean latitude of the 

 entire spotted area is farthest north about eight 

 months previous to the occurrence of a maximum 

 phase of the pressure wave over Iceland. A 3- 

 month period is shown to exist in spot and prom- 

 inence frequency and also in the Iceland pressures, 

 with variations in the length of the period con- 

 forming to variations in solar activity in the 

 3i-year cycle, i. e., the greater the activity the 

 shorter the period. Two shorter periods of about 

 33 days and 10 days have been detected in meteor- 

 ological phenomena, both of which undergo varia- 

 tions in length through a 3-month cycle. 



The 3J-year wave of pressure recedes from the 

 Iceland Low to the Azores High in fourteen 

 months, while the 3-month wave traverses the 

 same distance in forty days. The 10-day wave, 

 however, moves eastward around the globe, a con- 

 tinuous series of these waves having been traced 

 over the United States during the past three years. 

 This fact has an important bearing on recent 

 measurements of the intensity of solar radiation 

 at Washington and Mt. Wilson, the atmospheric 

 transmissibility being apparently greater at the 

 minimum phase of the 10-day temperature wave 

 than at the opposite phase. 



15. Professor Updegraff gave an account of the 

 progress made during the past year in funda- 

 mental observations of the sun and fixed stars 

 with the six-inch transit circle of the U. S. Naval 

 Observatory in conformity with the plan for fun- 

 damental work adopted by the observatory council 

 and approved by the superintendent. 



The repairs made necessary by deterioration 

 and the alterations of the instrument having been 

 completed, the instrument was mounted in Jan- 

 uary, 1909, and obser\'ations of stars were com- 

 menced on January 31. 



The form of the pivots and the stability of the 

 rotation axis of the instrument have been thor- 

 oughly investigated and have been found to be 

 highly satisfactory. The instrumental constants 

 are remarkably stable and are determined with a 

 satisfactory degree of accuracy, the probable error 

 of a determination of the azimuth from the marks 

 being ± 0=.006, of the level from the spirit level 

 ± 0^.006 and of the collimation from the col- 

 limators, ± 0^006. 



The transit micrometer has been brought into 

 use, and after practise the accidental errors of 

 the observers are no larger than is the case with 

 the chronograph key, which confirms the results 

 reported by other observers using that form of 

 instrument elsewhere in this country and in 

 Europe. 



The flexures of the telescope tube and the circles 

 have been partially investigated and have been 

 found to be small, the circles having no appre- 

 ciable flexure. A preliminary investigation of the 

 division errors of circle A has been completed and 

 the results are being used in reducing observations 

 in declination. 



A series of observations by Mr. Hammond of 

 stars direct and reflected has been reduced and a 

 small difi'erenee reflected minus dii'ect has been 

 found which gives on discussion a value of the 

 horizontal flexure the same as that obtained from 

 observations on the collimators. 



Satisfactory rates are given by the clocks in 

 the clock vault. The clocks are not, however, in 

 perfect order, as the bell jars leak somewhat, but 

 all difficulties seem to have been overcome in 

 regulating the temperature of the vault, which is 

 kept constant within a few hundredths of a degree 

 Centigrade for months at a time. 



More than 3,500 observations of stars have been 

 made in conformity with the plan for fundamental 

 work mentioned above. The main features of this 

 plan for fundamental work are as follows: 



The clock rate is determined fundamentally by 

 observation of the same clock stars by the same 

 observer at consecutive transits. 



The azimuth of the marks is determined by 

 observations of circumpolar stars at consecutive 

 transits U. C. and L. C. 



The latitude for the reduction of observations 



