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SCIENCE 



[Vol. XX. No. 516 



continues all night. One frequently finds it impossible to sleep 

 there though in the very best of health, and this is directly at- 

 tributed to the electric discharge, this fact is noted by Mr. Stone. 



To ray mind the most important line of investigation is that 

 regarding the connection between this discharge and the agglom- 

 eration of vapor molecules into cloud particles. Experiments 

 have already shown a most marked effect upon steam when an 

 electric discharge is passed into it. On Mt. Washington there are 

 dense clouds weeks at a time, while a mile or two from the sum- 

 mit the sky may be perfectly clear. A most careful study of 

 the phenomenon has shown that it could not be due to the rocks 

 of the summit being cooler than the air, as thought by many, for 

 the rocks were always warmer than the air except on nights 

 when there were no clouds. Nor could the persistent cloud be 

 due to the expansion and consequent cooling of air rushing up 

 the side of the mountain for the peak is a sharp cone at the last 

 500 feet and the cloud-hood extended on all sides to a mile or two. 

 It would seem probable that a careful study with instruments of 

 the phenomena of mountain electric discharges would shed a 

 great deal of light on the exceedingly complex subject of clouds 

 and rain- formation about wliich we know nothing except that the 

 ordinary theories need thorough revision. H. A. Hazen. 



Washington, D.C., Deo. 10. 



A Multiple Key. — Preliminary Note. 



In psychological laboratories it is frequently desirable to make 

 or break two or more electrical currents at the same instant. 



Ewald's key solves this problem for the most simple cases, but 

 a need for something more elaborate was felt. This led to the 

 invention by Dr. Scripture and the construction in the work-shop 

 of the Yale Psychological Laboratory of a multiple key which 

 meets all present requirements. Ewald's key costs 20 marks ; this 

 one, made by the laboratory mechanic, of unlacquered brass, 

 without platinum contacts, was made at a cost of less than $10. 



It is arranged so that five currents can run through it. One, 

 two, or three of these can be made and one broken at the same 

 time. The other can either be made or broken at the same time 

 or broken for an instant and then made again ; or these makes 

 and breaks can be adjusted so as to occur one after the other in 

 any order. By reversing the key, it gives three breaks and two 

 makes. 



An illustration of the use of the key can be taken from one of 

 the problems in reaction time now being investigated. A single 

 movement of the key first breaks the shunt of the tuning-fork 

 circuit and starts the time-marker vibrating on the recording 

 drum; an instant later, say, .03 of a second, it closes a telephone 

 circuit running to the reacting-room from the sound-room, thus 

 producing the stimulus; it simultaneously breaks a current run- 

 ning through the registering signal on the drum and a closed key 

 in the reaction room. This current is automatically closed again 

 within .03 of a second, and again broken by the reaction on the 

 closed key. As soon as the reaction takes place, the key is re- 

 leased and the tuning-fork curve stopped before the drum has 

 made a complete revolution, thus saving all motion of the marker 

 during the experiment, as well as space on the smoked paper. 

 This not only saves much time, but also renders the records more 

 legible and consequently more accurate. 



Charles B. Bliss. 



New Haven, Conn., Dec. 19. 



Excitement Over Glacial Thtories. 



Probably I have as much reason to be thankful for the frank- 

 ness of Mr. McGee's letter in Science for Dec. 3, as for the cour- 

 tesy of Dr. Brinton's previous review of my volume on " Man 

 and the Glacial Period," for it doubtless gives expression to sen- 

 timents held by many persons in private, and it is better that I 

 should have occasion to explain the misapprehensions which 

 evidently prevail in some quarters. I beg, therefore, the privi- 

 lege of your space for a brief statement of some points. 



Mr. McGee refers to an apparent discrepancy between my ob- 

 servations on the rate of movement of the Muir Glacier and those 

 of Professor Reid. If he had read Professor Reid's article care 



fully he would have seen that the discrepancy is more apparent 

 than real. Professor Reid distinctly states that there was a quar- 

 ter of a mile or more of width in the glacier which he was un- 

 able to reach with his stakes, and whose motion he therefore 

 failed to measure, whereas by our method of taking angles di- 

 rectly upon the ice-pinnacles we were able to measure the por- 

 tions which were presumably moving most rapidly. 



As to my connection with the U. S. Geological Survey, the 

 facts are that after I had, on the Pennsylvania Survey and at 

 much private expense, mapped the glacial boundary from the 

 Delaware River to Illinois, and published the results with con- 

 siderable fulness, I was asked, in 1884, to complete the work to 

 the Mississippi River for the U. S. Geological Survey and prepare 

 a report on the whole line from there to the Allegheny Moun- 

 tains. This I did, and the report was duly published in 1890. 

 My formal connection with the Survey did not terminate until a 

 month after the publication of my last book. I am not aware 

 that any substantial error has been pointed out in my delineation 

 of the southern border of the ice-sheet, which I was set to accom- 

 plish (see Tlie Dial for Dec. 16, 1893). 



The real point at issue relates to the question of the unity, or 

 one might better say the " continuity" of the glacial period, and 

 the disturbance all arises over the fact that I have been led to 

 interpret the facts in accordance with the theory of glacial con- 

 tinuity, while Mr. McGee and some of his associates are com- 

 mitted to the theory that there were two or more distinct epochs. 

 It is sufficient for me here to say that my conclusions are based 

 on a large amount of field-work, and are supported by a respect- 

 able number of able geologists, and have recently been set forth 

 at considerable length in an article in the November number of 

 the American Jmirnal of Sciencf. In this I have not wholly disre- 

 garded Mr. McGee"s science of geomorphy though I have not 

 called it by that name. 



Perhaps the best way tor me to answer the charge of general 

 ignorance will be to state in a few words the conception of the 

 progress of events during the glacial period which I have been 

 slowly led to entertain. 



During the most of the Tertiary period the lands were low 

 towards the pole and a warm climate prevailed. Toward the 

 close of the Tertiary a slow elevation of these northern lands was 

 in progress until they stood, say, 8,000 feet higher than now. 

 This is shown by the fiords which characterize both sides of the 

 continent from the latitude of Chesapeake Bay northward. 



This elevation of land was probably the predominant cause of 

 the glacial period, for the ice-movement in North America radi- 

 ated, not from the pole, but from Labrador and the region about 

 Hudson Bay. This elevation was accompanied by a rapid deep- 

 ening of the river channels over the area and the consequent ac- 

 cumulation of detritus about their mouths. 



Ice finally accumulated nearly a mile deep over the area north 

 of thelinemarking the " drift" and extending to New York City 

 and Cincinnati. This accumulation of ice was coincident with, 

 if not the cause of, a depression of the land in the more northern 

 portions several hundred feet below its present level. 



The final melting of the ice proceeded with great rapidity, but 

 with various halts and oscillations of the front. The period of 

 oscillation of the glaciers in the Alps is something like half a 

 century. The periods during the great ice age were probably 

 much longer, but a few centuries seems ample to account for the 

 longest. These oscillations are marked by what Professor Cook 

 aptly called "moraines of retrecession,'' of which there are 

 twelve in Ohio. 



Applying the principles of Mr. McGee's science of geomorphy, 

 I explain the phemimena of slackened drainage which charac- 

 terize the deposits along the extreme margin of the glaciated 

 area as connected with the subsidence of the land increasing to 

 the north, which marked the climax of the period, while the 

 more vigorous signs of drainage action farther north are the 

 natural results of the northerly re-elevation which went on syn- 

 chronously with the unloading of the weight of the ice by melt- 

 ing. It is in these later stages of the deposition of ground that 

 we find the remains of palaeolithic man. 



Whether this theory of the progress of events is correct or not. 



