^28 



SCIENCE. 



[Vol. XIV. No. 359 



■when in a horizontal position. In order to reach some definite re- 

 ■sults, glass rods of different diameters were used. They were so 

 -arranged as to allow an increase of their weights by attachments, 

 -and so that the hand might be applied in a perpendicular position. 

 When first examined, on Sept. 22, it was found that the extreme 

 limit of weight which could be made to adhere, by means of a glass 

 rod of 10 millimetres diameter, to the surface of the front part of 

 the four fingers of the right hand, when held perpendicularly, was 

 1,450 grams. A glass tube of 20 millimetres diameter was next 

 substituted, and would yet adhere when its weight had been in- 

 -creased to 1,900 grams. 



When the experiments were repeated on subsequent days, the 

 ■same glass tube could each time ,be loaded heavier, and Mr. H. 



■ can now lift the comparatively enormous weight of 2,5lo grams, 

 -after having pressed his fingers tightly to the glass rod, which 

 stands in a perpendicular position upon a metallic disk to which it 

 is fastened, and which also carries the weights. 



I ought to state that the thumb is never used to cause the ad- 

 hesion, and that, in commencing a series of experiments, Mr. H. 

 can never at the beginning lift the greatest weight. It appears 

 that the power of adhesion increases during a series of experiments 

 made within a period of fifteen or twenty minutes. So far, the 

 power has continued to increase almost from day to day, but ap- 

 pears to have now reached its maximum. Following are the re- 

 sults of a few of the experiments made as described above; the 



'first figure representing the diameter of the glass tube (in milli- 



'Hietres), and the second the maximum weight suspended (in grams) : 

 5, 1,530; 10, 2,120; 15, 2,400; 20, 2,610; 25, 2,260; 30, i,S6o. 

 The weights recorded above are nearly one hundred times 



•greater than those which can be lifted by adhesion when the cor- 



•-responding tubes are used horizontally. Exact measurements of 

 that portion of the hand's surface which comes in contact with the 

 adhering mass are difficult to make. However, the determinations 

 were made sufficiently accurately to show that very nearly 3 square 

 centimetres surface enter into action during the adherence of a 20- 

 millimetre rod, when supporting 2,500 grams. 



When the investigation was first begun, Mr. H. not only firmly 

 believed in his utter inability to use his left hand as he did his right, 

 but also looked for the seat of the adhesive power only in the front 



-part of his fingers. It has now been demonstrated that the left 

 hand does all the work equally as well as the right one, and that 

 the surface of adhesion extends, though different in intensity, over 

 almost the whole of the inner part of the hands. The power is 

 strongest in the front part of the fingers, and weakest in the centre 

 of the palm and on that portion of the fingers which is nearest to it. 

 All the protruding portions, including the ball below the thumb, 



■possess adhesive power, however. Neither the back of the hands, 

 nor other parts of the body, including the surface of the 

 soles and toes, show any signs of adhesion. The power of the 

 hand to sustain objects may be shown by suspending upon it, for 

 instance, four 6- inch test-tubes alongside of one another, or by ap- 

 plying an iron rod, a wooden stick, and a glass tube simultaneously 

 to different parts of the hand. A test-tube adhering to the hand 

 may be made to roll to and fro by jerking the hand backward and 



-forward while the tube is in a perpendicular position. 



The intensity of adhesive power in the various fingers differs 

 widely. It is strongest in the index and middle finger, and weak- 

 est in the little finger ; the latter doing so little work, that the three 



■ others may lift almost as much as the four. What is most singular 

 is that one finger possesses very little power. The greatest weight 

 shown to adhere to one finger has been about 35 grams, while two 

 fingers may lift 1,400 grams. In order to decide whether or not 

 ■the aid given by a second or third finger, in balancing or steadying 

 the weight of the suspended mass, was the cause of this inability 

 of one finger to do much work, three fingers were covered with a 

 thin film of collodion, which rendered them unfit to act by adhe- 

 sion, but not by their muscular support. 



The experiments thus performed showed conclusively that the 

 three fingers covered with collodion were absolutely unable to as- 

 sist the fourth one. It can therefore not be the steadying power 

 which causes two fingers to do forty times the work of one finger. 

 That this should be so, might have been inferred from the fact that 

 .Mr. H. can suspend a combustion tube about four feet long on two 



fingers, and cause it to swing like a pendulum through a distance 

 of at least three feet. 



The length of time during wnich substances adhere depends 

 chiefly upon their weight. Light objects, such as test-tubes, will 

 remain suspended even horizontally for ten minutes or longer, and 

 can then be removed only by the application of some force, when a 

 slight click, caused by the concussion of air, can be heard. Very 

 heavy articles will fall off sooner ; but whether in consequence of a 

 diminution in the adhesive power of the surface, or in consequence 

 of the strain exerted upon the muscles, it is difficult to say. An- 

 other cause of the falling-off is to be found in the perspiration 

 which at times oozes freely from the pores, and interferes greatly 

 with the experiments. 



It may be added, that neither the shape of Mr. H.'s hands nor 

 the structure of the skin, even when examined under a magnifying- 

 glass, shows any thing abnormal, though the skin is very soft and 

 smooth. These are the principal results of the investigation made, 

 and the next question is, how to account for the phenomenon. I 

 need not mention the reasons which exclude the possibility of an 

 electric or a magnetic action, because the facts presented show 

 this conclusively. We therefore seem to be limited to a con- 

 sideration of surface action, or atmospheric pressure, or both. 

 The reasons for this assumption are, (i) that it has been found 

 impossible to notice any attraction whatever exerted at a distance ; 

 (2) that the power increases with the cleanliness and smooth- 

 ness of the surface, i.e., with the number of actual points of con- 

 tact ; (3) that the peculiar sound heard on breaking contact is 

 characteristic of the concussion of air ; (4) that the power increases 

 with the increase of surfaces in contact, as shown in the experi- 

 ments with glass tubes of different diameters.' 



Whether, or to what extent, the pressure of atmospheric air in- 

 duces these phenomena, I am unable to say. I have not had an 

 opportunity to examine Mr. H. under a diminished or increased 

 pressure, but hope to do so ere long. Certain it is, that the ratio 

 of one square inch of adhering surface to fifteen pounds in sus- 

 pended weight has not been exceeded, though approached to with- 

 in twenty per cent. But even if air-pressure participates, as it 

 most likely does, we have to assume that the skin of Mr. H. is 

 peculiarly fitted to show these phenomena of skin-adhesion, and in 

 a degree, to my knowledge, unnoticed heretofore. That he is not 

 the only person possessing this power, I have good reason to be- 

 lieve. Among a large number of people examined, there were 

 many whose hands showed at least signs of this power, and cer- 

 tainly a few who promised to develop it sufficiently to exclude 

 doubt in regard to the occasional existence of the force. It may 

 be well to warn persons who may try experiments, not to mistake 

 for actual adhesion the suspension of tubes by means of counter- 

 pressure exerted by portions of the terminal phalanges or the fleshy 

 portions surrounding them. The unmistakable sign of adhesion is 

 the performance of the experiments with the fingers kept absolutely 

 close to one another, in which case it becomes next to impossible to 

 exert counter-pressure. That muscular action may come into play 

 in some of Mr. H.'s experiments is not absolutely impossible, yet 

 very doubtful. I leave it to physiologists to furnish a more satis- 

 factory explanation of these phenomena than I myself have so far 

 been able to give. W. Simon, Ph.D. 



Baltimore, Dec. i6. 



Convectional Currents in Storms. 

 Readers of Science will remember, that, in the numbers for 

 May 10 and June 21 of the current year, there were given some 

 computations of the probable effect of convectional currents and of 

 the condensation of moisture carried by them into the cooler air 

 strata above. These computations showed that there could be no 

 liberation of energy from any such action. An interesting article 

 has appeared in the American Meteorological Jottrnal iox Decem- 

 ber from the pen of Professor Davis of Harvard University, in 

 which I find, " It is difficult to understand why this question should 

 be so confused by Hazen, as appears in his recent articles. . . . 



1 That there is a decrease in power when the tubes are wider than 20 millimetres 

 may be explained by the fact that those surfaces of the fingers which show the high- 

 est degree of adhesion are prevented from coming in proper contact with the surface 

 of tubes, when of too large a diameter. This would account also for the poor adhe- 

 sion of objects with flat surfaces. 



