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THE POPULAR SCIENCE MONTHLY. 



marks by various members of the Society 

 followed the reading of the paper ; they are 

 briefly stated in the " Monthly Journal of 

 Science," and are, on the whole, favorable 

 to Mr. Brearey's views. Mr. Glaisher saw 

 no reason why the balloon should not be 

 made available in arctic exploration, and 

 he hoped that, if there were another expe- 

 dition, the balloon would be tried and the 

 question settled. It would certainly, if used 

 in connection with a sled, enable the ex- 

 plorers to travel much more rapidly than 

 they can at present. Touching on the use of 

 the balloon as an observatory, he said that, 

 when he was only half a mile over London, 

 he could see Margate and Brighton. This 

 showed how much may be seen from a com- 

 paratively small elevation. 



A Blood-sucking Squirrel.— Dr. Richard 

 E. Kunze gives in "Science News" an en- 

 tertaining account of a pair (male and fe- 

 male) of pet gray squirrels, one of which, 

 the male, he detected in the act of sucking 

 the other's blood. Having noticed that the 

 female looked emaciated, and that in mov- 

 ing about she dragged a hind leg, Dr. Kunze 

 made an examination, which resulted in the 

 discovery of a circular hole in this leg direct- 

 ly over the hamstring muscles, extending 

 through the entire thickness of the skin. 

 The edges of this opening, or sore, which was 

 of the diameter of a lead-pencil, looked 

 smooth and blanched. Now, it could not be 

 the result of a puncture or any other wound, 

 because there was present neither inflam- 

 mation nor discbarge. It had the appear- 

 ance of an artificial issue, was sensitive but 

 not painful. For a time he was puzzled to 

 account for the hole, but at last he caught 

 her companion in the act of sucking her 

 blood. The " vampire " was seen to bury 

 his snout deeply in the fur m the direction 

 of the sore. Soon the female squirrel, 

 which had before been asleep, gave a sharp 

 cry. " My suspicions," writes Dr. Kunze, 

 " were soon confirmed, that he was actually 

 sucking out the very life-substance of his 

 mate. For several days a number of medi- 

 cal friends kept a sharp lookout on Foxie's 

 unnatural conduct. At first we simply 

 drove him away from his mate whenever he 

 was intentionally too near the coveted spot. 

 We now had to beat him off. In propor- 



tion as we resorted to such severe measures, 

 Foxie became more cunning, and with an 

 Argus-eye would watch his chance to act 

 unobserved. Finally, he became much 

 bolder in his onslaughts. He would seize 

 the leg whenever he could get hold of it. I 

 have seen him time and again place both 

 hands on each side of the ' sore,' appar- 

 ently gently pressing down the edges, just 

 as a little kitten in nursing would keep up 

 a pressure on the milk-ducts, and simulta- 

 neously suck with all his might." 



Blindness and its Causes.— According to 

 the last census returns there were, in the 

 United Kingdom of Great Britain and Ire- 

 land, 81,159 blind persons, or one in 1,015 

 of the population. The proportions in dif- 

 ferent parts of the kingdom vary greatly, 

 from one in 635 in Cornwall to one in 1,367 

 in Durham ; the proportion being higher in 

 agricultural than in urban districts. It is 

 gratifying to learn that though the actual 

 number of the blind increases, their propor- 

 tion to the seeing population diminishes — a 

 change which is probably due partly to the 

 improvements in ophthalmic surgery, partly 

 to the greater attention paid to the laws of 

 hygiene. But that there is still room for 

 much improvement in the latter respect is 

 only too apparent from the imperfect re- 

 turns of the causes of blindness made by the 

 directors of a few schools for the blind. 

 Thus the report of the York School shows 

 that out of 82 pupils 36 lost their sight 

 from purulent ophthalmia. And similar re- 

 sults are observed in countries on the Euro- 

 pean Continent. For instance, according 

 to Marjolin, out of 208 pupils in the Paris 

 Institution for the Blind, 80 became blind 

 from this disease, and 18 from small-pox; so 

 that one half lost their sight from preventa- 

 ble causes. In the institutions of Germany 

 the loss of sight from purulent ophthalmia 

 is stated to be about 30 per cent. 



The impairment of eyesight by habitual 

 protracted reading has been made a special 

 subject of study by M. Javel, a French phy- 

 sician, who also proposes a method of re- 

 ducing to a minimum the damage so caused. 

 In the first place, reading requires an ab- 

 solutely permanent application of eyesight, 

 resulting in a permanent tension of the or- 

 gan. Secondly, books are printed in black 



