DEEP-SEA INVESTIGATION. 59 



irradiation from the white paper, and recommends a thickening of the 

 cross-strokes at the ends to obviate this defect. This observation is 

 less applicable to the Geiman letters, for they already have broken 

 lines and knobbed expansions at the ends of the strokes. Many 

 physicians, particularly those who are not Germans, believe that the 

 shape of the German letters is more tiresome to the eyes than that of 

 the Roman letters, I have never been able to perceive this, nor any 

 reason why it should be so, provided the German print is large and 

 thick enough, and the lines are far enough apart. Use has doubtless 

 much to do with the matter. For myself, it is always pleasant, after 

 a long reading of the monotonous Roman print, to return to " our 

 beloved German." 



Even the thickest and largest letters, the shortest and best sepa- 

 rated lines, and the most excellent printing, may speed the progress of 

 myopy if the light is bad. At home, every one can find a light place 

 to read by the window on dark days, by a bright lamp at night. It 

 is different in schools and ofiices. Fifteen years ago, after measuring 

 the ratio of the window-space to the floor-space in the schoolhouses of 

 Breslau, I declared that there could never be too much light in a 

 schoolroom, and estimated that unless the house could be furnished 

 with a glass roof, at least thirty square inches of window-space should 

 be provided for each square foot of floor-space. In many schoolrooms 

 as at present arranged, the pupils nearest the windows may be sitting 

 in a glare of light, while those farthest away are not able to study for 

 the obscurity. Notwithstanding all that has been written and all that 

 has been done in the last fifteen years for the improvement of school- 

 rooms, enough is still left to be clone in nearly every town. Deutsche 

 Hundschau. 



--^ 



DEEP-SEA IXYESTIGATIOK* 



By J. G. BUCHANAN, F. E. S. E,, 



OF THE CHALLENGER EXPEDITION. 



T 





IHE first problem of deep-sea investigation is to determine the 

 extent of the ocean, its size, its volume. The superficial extent 

 and limits are determined by the surveyor. In order to map out the 

 bottom of the sea, there is only one method, namely, the direct de- 

 termination of the depth at as many places as possible. When a ship 

 is "in soundings," the depth is ascertained by the ordinary hand lead- 

 line, which is from twenty to twenty-five fathoms long, and is con- 

 ventionally marked at stated intervals with bits of leather, white, 



* Abridged and condensed from an address delivered before the Society of Arts, Feb- 

 ruary 24, 1881. 



