Popular Science Monthly 



915 



The submerged dry dock was placed under the stern of the cruiser and then pumped out, 

 thereby lifting the stem out o'f the water. This remarkable feat took place at Honolulu 



A Four-Hundred-Foot Ship in a 

 Three-Hundred-Foot Dock 



THE unusual feat of dry-docking a 

 ship of four hundred and forty-six 

 feet in length and a displacement of 

 9,300 tons in a dry dock only three hun- 

 dred feet long and with a lifting capacity 

 of 4,500 tons, was accomplished a short 

 time ago, when the Japanese first-class 

 cruiser Azuma, the propeller of which 

 had been damaged, was docked for re- 

 pairs in a floating dry dock at Honolulu. 

 In order to carry out this undertaking, 

 the dock was submerged and placed under 

 the stern of the cruiser and then pumped 

 out. It is said to have been the first time 

 that this seemingly im.possible feat was 

 attempted. The result was extremely 

 gratifying, and the remarkable procedure 

 is sure to find imitators elsewhere. 



Thirty Million Collisions in a 

 Day — the Earth's Record 



ASTRONOMERS have collected a 

 , great deal of material in recent years 

 which seems to prove that there is an 

 enormous mass of non-luminous comet or 

 meteorite material scattered through 

 stellar space. It is estimated that as 



many as twenty or thirty millions of such 

 bodies collide with the earth every 

 twenty-four hours. Assuming a fairly 

 even distribution of these cosmic particles 

 in space, their quantity and number must 

 be beyond computation. Clouds of such 

 particles are now believed to be the cause 

 of the dark and starless areas in regions 

 where bright stars are numerous. It is 

 assumed that clouds of meteorite material 

 prevent us from seeing the stars beyond 

 in these particular regions of space. The 

 dark spaces in the Milky Way, the so- 

 called "coal sacks" in the constellation of 

 Sagittarius and many other starless re- 

 gions are accounted for in this manner. 



Photographic star records made at 

 Harvard and elsewhere during recent 

 years have supplied much valuable in- 

 formation to support the theory that the 

 so-called new stars, also known as tem- 

 porary stars, which flash out at points 

 where previously no stars were known to 

 exist, are stars which suddenly become 

 luminous by passing through a cloud of 

 meteoric particles. While passing 

 through the cloud the faintly luminous 

 star is in effect bombarded at high 

 velocity by the meteoric cloud. The sur- 

 face strata become heated and the lumi- 

 nosity of the star increases rapidly. 



