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THE POPULAR SCIENCE MONTHLY. 



be made of pasturage beyond a reasonable 

 distance from springs. This area is there- 

 fore eaten down to the ground, while suc- 

 culent pasturage beyond it goes to waste. 

 Hardly more than one fifth of the extent of 

 the high plateau, for this reason, is avail- 

 able. Algerian wool is Arab or Berber. 

 Arab wool is generally of a short fiber, 

 sometimes moderately, rarely very long, and 

 regulated as to length by the climatic influ- 

 ences of the localities where the sheep are 

 raised. It is always short on the high pla- 

 teaus, and becomes longer as the sheep de- 

 scend into more fertile and better watered 

 regions ; but in both instances it is pure 

 wool, of a fine quality, and without any 

 hairy appearance. Berber wool is hard and 

 coarse, and is confined to mountainous and 

 sometimes inaccessible regions, where there 

 is constant pasturage, and the migration of 

 flocks in the summer season is unnecessary. 



Care of onr Eyes. Few persons are 

 aware, says M. Felix Hement, that besides 

 size, shape, and color, their eyes differ in 

 visual force and in power of accommodation ; 

 and also that some faults affect only one of 

 them. It is an established fact that we all 

 use one eye the right or the left in pref- 

 erence, when looking through a glass or 

 taking aim with a gun. We are right- or 

 left-eyed as we are right- or left-handed or 

 footed. If we do not perceive this our- 

 selves, oculists and opticians remark it. The 

 ignorance of most people on this subject is 

 illustrated by their buying glasses at the 

 opticians without taking account of any dif- 

 ference between the eyes. Thus only one 

 of the eyes is helped, while the other one, 

 being less called into exercise, becomes less 

 and less useful, and loses its powers as a 

 tool rusts when it is not in use. Yet both 

 our eyes are needed to see well. It becomes, 

 therefore, highly important to observe how 

 the child uses its eyes, in order to correct 

 those attitudes which tend to injury of the 

 sight as well as of the health. Children, in 

 writing, rarely fail to give the head an in- 

 clination by which the eyes are placed at 

 unequal distances from the paper. They 

 are also apt to incline their head too far, 

 and acquire the habit of bringing it too near, 

 as when they try to accommodate themselves 

 to a feeble light. Not sufficient attention, 



we think, is given to these matters, espe- 

 cially when we consider the consequences of 

 such habits in mature age. A large pro- 

 portion of our defects originate in want of 

 proper care during childhood. We do wrong 

 to such wonderful tools as our senses when 

 we do not give them the education they 

 need. Is it not surprising that parents who 

 are so particular about the way their chil- 

 dren hold their fork or spoon pay so little 

 attention to the way they use their eyes ? 



Stone Chips. Describing to the Ameri- 

 can Association the aboriginal stone imple- 

 ments of the Potomac Valley, Washington, 

 D. C, Mr. W. H. Holmes said that they were 

 of soapstone, quartz, and quartzite. The 

 Algonquin peoples quarried the soapstone 

 to get stuff for vessel-making. The quartz 

 and quartzite were made into spear-heads, 

 arrow-points, and knives, and the material 

 was obtained from bowlders dug from the 

 bluffs. In shaping the implements, which 

 was done by percussion, thousands of stones 

 were thrown aside because of flaws. Leaf- 

 shaped blades were made at the quarries 

 and carried to the villages to be finished. 

 When the village was at the quarry-site, 

 relics of all the stages of progress were 

 found in the refuse. Where the villages 

 were not located on the quarry-sites, no rude 

 forms were found, but only the blades and 

 the fully finished tools made from them. 

 Hence, the author contended, the rude forms 

 of chipped stones are not tools at all ; and 

 the difference between the " rough stone 

 age " and the " smooth stone age," insisted 

 upon by French archaeologists, disappears. 

 Mr. Holmes was supported by Prof. Putnam, 

 but Dr. 0. L. Mason was not ready to see 

 their theory so summarily disposed of. 



Onr Most Esnal Words. Prof. Jastrow 

 communicated to the American Association 

 a curious study of processes involved in 

 every-day mental life. Twenty-five men and 

 twenty-five women, students in a class in psy- 

 chology, wrote as rapidly as possible the first 

 hundred words that occurred to them. Of 

 the five thousand words written only 2,024 

 words were different. Twelve hundred and 

 sixteen words occur but once in the lists. 

 Omitting these, about three thousand of the 

 words were formed by the repetition of only 



