VOL. II.] PHILOSOPHICAL TRANSACTIONS. ^f^^J 



for mutual assistance in reading, when they are thus far divided by tubes gi that 

 length. The lighter the stuff is, the less it will encumber. Remember always 

 to black the inside with some black that has no lustre or glittering. And you 

 should have the tubes so moveable, that you may draw them longer or shorter, 

 allowing also the orifice wider or narrower, according to circumstances. 



I have not tried what glasses will do if settled in these tubes, having no need 

 of them. Probably they may be more proper for some that are squint-eyed, 

 whose eyes interfere. Certainly it will ease those that cannot well bear the 

 light ; and perchance it will preserve the sight for a longer time. 

 In another letter the same person adds: 



I see now, by these taper tubes, as well as the youngest in my family, and can 

 read the smallest and most confused prints through them as well as ever I could 

 from my childhood, though my sight be almost lost. And having used these 

 empty holes for spectacles little more than a week, I can now use them without 

 trouble all the day long; and I verily believe, that by this little use of them, my 

 sight already is much amended. For I now see the greenness of the garden, 

 and pastures in a florid verdure, whereas very lately dark colours, blue and green, 

 had the same hue to my eye. 



If you ask me, how this device came in my head, I shall tell you all I know. 

 Some years ago I was framing one of Hevelius's polyscopes ; as I was trying 

 the tube, without the dioptric glasses, I perceived that though the tube took in 

 very little, and seemed scarce serviceable for any considerable purpose; yet the 

 object appeared to me more distinct and clear through the tube, than through 

 the open air. This I recollected, and thereupon made the trial, and found the 

 effect fully answer to my case. 



As for your trial of the tubulous spectacles, the tubes may be of paper, only 

 coloured black and pasted on, and with the inner folds drawn out from one inch 

 to three; some of the folds to be taken out, that the orifice may be w^der or 

 narrower, as best fits to every degree of defect. 



Of the Antiquity of the Transfusion of Blood from one Animal to 



another, N" 37, p. 731. 



There has been of late some contest about the origin of transfusion, the 

 English first claiming it as a late invention of theirs, the French pretending 

 thereupon, that it had been proposed among them ten years ago : after which, 

 it was afiHrmed upon further investigation, by some ingenious persons in Eng- 

 land, that it had been known there 30 years ago ; (whereof the publisher of 

 these Tracts has good proof in his hands) . But it seems, that an Italian philo- 



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