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for he had only a choice between two things, one of which was right and the other wrong. The number of correct answers above one-half the total number of answers would measure the magnetic sensibility.

Experimenting in this way, we were surprised to find that considerably more than one-half the answers were correct. Apparently the magnetic sense was there. But it was soon observed that we more or less consciously judged by the sound that the turning of the dynamo transmitted along the wire, and thus to the magnet. When the attention was once directed to this point, the doings of the operator could be correctly told every time. After many failures, we succeeded in eliminating this sound by cutting the wires, and inserting one end of each into a mercury-cup, and connecting the other by a binding-screw with the cup. The wires were suspended from the ceiling by silk threads, and inserted freely in the mercury: in this way the sound-vibrations were transmitted to the mercury, and only very weakly taken up again by the wire. This arrangement was inserted in the circuit once in the basement room, and again on the sill of the window, as the wires passed the second floor of the building. The turning of the dynamo was thus rendered inaudible; and for a time the results were negative, the number of correct answers being just about one-half of the total number of experiments. But soon the correct answers became more and This time more frequent. the indications were more subtle. As is well known to physicists, the magnetization and demagnetization of a powerful magnet produce a molecular crepitation throughout its mass, which gives rise to a very faint but audible click. It was this click, and not the magnetic sense, that told us when the current was being turned on, and when off. It is remarkable that we used this click as an indication of the condition of the magnet long before we were distinctly conscious of its existence. This click could not be heard every time, but, with the attention sharply focused, almost every time. But it will be objected, as the click accompanied each change,' it could not guide the judgment of the subject. This objection would hold were it not that the click accompanying demagnetization is much more pronounced than that accompanying magnetization. In fact, the latter could rarely, if ever, be distinctly heard.

These difficulties were obviated by a slight alteration in the mode of experimentation. At the beginning of each experiment the current was off; at the signal of Change,' the current was either turned on or left off. The subject had then simply to decide whether, on the whole, something had been going on during the experiment, or whether the

dynamo had not been turned at all. In this way, only the magnetization, and never the demagnetization, occurred in the experiments, and the click was thus avoided. Moreover, to completely guard against the very slight click of magnetization, the current was not made as formerly, by the closing of a key; but, with a key always closed, the dynamo was turned with gradually increasing speed. It is the suddenness of the magnetization that produces the click. It is evident, that, as before, the chances of a correct guess are just onehalf. The opportunities for judging are perhaps not as favorable when only one change is made, but it is doubtful whether even this difference is appreciable. It is this latter method that was used throughout the rest of the experiments. In all, ten persons, all students in good health, were experimented upon, including Dr. Nuttall and the writer. The results are given in the following table:

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This table makes it evident, that, in the case of those experimented upon, no sensibility for a magnetic field existed. This still leaves the question open, whether there may not be a morbid sensibility for such an effect; but it makes such a possibility less probable, because the sensibility for a magnetic field ascribed to sensitives' is so intense, that some slight remnant of it might be expected to exist in normal persons. It was intended to test persons who were good hypnotic subjects both in the normal and the hypnotic conditions, but no opportunity offered itself. Our conclusions refer only to the question of a normal magnetic sense.

On what ground the alleged magnetic phenomena are to be explained is another and more delicate question: that the imagination is a powerful and important factor is beyond doubt; and when, as is generally the case, morbidly sensitive patients, especially hysterical girls, are experimented upon, the merest trace of a suggestion, unconsciously given, of the desired or expected effect, is enough to bring about all the phenomena of transport,' etc., for which the magnet has been held accountable. Only when tested under

rigid and scientifically controllable conditions can the evidence of such abnormal sensibility be relied upon. Even the precautions against indications as above described would probably have to be added to, if hypnotic subjects were experimented upon.

In conclusion it is desired to lay stress not only on the negative character of the results, but on the method employed, and especially on the fact, that, as the precautions were rendered more and more effective, the negative character of the conclusions became more and more evident.'



No more interesting and valuable report has been presented to parliament during the recent session than that of the inspectors of explosives for 1885. Colonel Majendie and his colleagues have been engaged for ten years in protecting the public against the most terrible dangers to which modern science has exposed it. A list of twentynine men is given who have been caught and punished for complicity in what are usually known as dynamite outrages. In 1885, 133 ordinary explosions due to accident came under the notice of the Home office, and some almost incredible stories are told of carelessness in connection with explosives. The explosion of tablets of chlorate of potash in the pocket of a gentleman in Brookline, Mass., who dropped his watch upon them quickly, is characterized as the most curious explosion of the year. Among other explosive medicines' is mentioned nitro-glycerine, which is made up with lozenges, etc., for use in cases of angina pectoris and other complaints. In the United Kingdom, 22,268 houses are registered for the keeping of explosives. It is the duty of the local authorities to see that the provisions of the act are complied with. Sometimes, however, they are very remiss, and the inspectors act as a useful check upon them. In 1885, 392 places where explosives were kept for retail sale were inspected, and in some cases they were found to be about as bad as they could be.' London, Liverpool, Bristol, Birmingham, Sheffield, Huddersfield, and Bath are selected for special commendation in this respect.

At the last meeting of the London section of the Society of chemical industry, a very valuable paper was read by Dr. Meymolt Tidy on the chemical treatment of sewage. Premising that

The above is simply a general account of the experiments. For a detailed account, the reader is referred to the full paper on the subject, to appear in the next number of the Proceedings of the American society for psychical research.

he had for many years read every thing he could get hold of on the subject, and had also gained practical personal experience therein, he defined sewage as " the refuse of communities, their habitations, streets, and factories." Its very complex nature was commented upon. Two elements were constant, and the rest nowhere:' viz., 1°, excreta (every thousand people gave, on a very large average, 2,640 pounds of liquid, and 141 pounds of dry, sewage daily); 2°, roads (if woodpaving be excluded, road-washings contained, on an average, 280 grains of solid matter per gallon, of which 120 were in solution). The extreme difficulty of obtaining fair samples was amusingly commented on; and the salutary effects on sewage, of air and of dilution, as shown by the appearance therein, or otherwise, of comparatively high forms of microscopic life, such as the Vorticella, Rotifera, etc., was pointed out. An unfailing characteristic of sewage was the presence of hairs of wheat, and of free spiral cells, their casing having been dissolved in digestive processes. Authorities were agreed upon two points; viz., that the valuable matters were in solution, and the offensive in suspension. Irrigation could

not be relied on for giving absolutely continuous purity. Of the precipitation processes, those in which lime and alumina were employed successively, gave the best general results; and the smell still remaining might be entirely got rid of by causing the effluent to flow over a little land. This combination was probably the best method of dealing with liquid sewage; but, in Dr. Tidy's opinion, the whole system of water-carriage of sewage was a mistake. It was absurd to take expensive and elaborate precautions about purity of water-supply, and then only to use one-ninetieth of this for drinking, allowing the rest to be polluted. The dry-earth system of dealing with human excreta was the only proper and scientific method.

The second, and ladies', conversazione of the Royal society was held on the evening of June 9. Many of the objects of interest exhibited at the former one were on view again. Among the novelties were the following: some microscopic sections, diagrams, and specimens illustrating the alteration artificially produced in vitreous rocks by the action of heat alone, by Mr. F. Rutley; floral studies in Chili, of orchids, nests, etc., by Miss North; illustrative diagrams of and specimens from Roraima; some rare earths from Samarskite, Gadolinite, etc., with illustrations of their phosphorescent spectra, by Mr. W. Crookes; pumice, volcanic ash, drawings, diagrams, etc., illustrative of the great volcanic eruption, by the Krakatoa committee of the Royal society; ap

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The annual meeting of the Marine biological association was held on June 8, Professor Huxley, the president, in the chair. The council's report mentioned a small increase in the number of members during the year, and the progress that has been made with the plans for the new laboratory at Plymouth, which will be commenced immediately. It is hoped that it may be in working order by the autumn of next year. Much interest is taken in it by the residents of Plymouth, one of whom, hearing that the council of the association were contemplating the omission, for pecuniary reasons, of certain desirable features in the building, has generously offered to provide the five hundred pounds necessary for the purpose.

A large amount of valuable zoölogical work has been recently carried out by the Liverpool marine biology committee, which was established some two years ago. The shallow water off the coast of North Wales and round the Isle of Man has been systematically explored with the dredge, with the following very gratifying results : whereas only 270 species of marine invertebrates were known from this neighborhood before 1853, 913 species are recorded in the report of the Liverpool committee. Of these, 235 were not previously known in the locality; 16 are new to British seas; while 7 species and 3 varieties are new to science.

London, June 14.



THE Lackawanna institute of history and science, recently founded at Scranton, Penn.. has taken steps for the purchase and preservation of the two great glacial pot-holes found in the Lackawanna valley at Archbald. An illustration of one of these pot-holes was published in Science for Dec. 19, 1884. The second one has not yet been cleared out, but will be cleared by the Lackawanna society. These holes are described by Professor Branner in his recent paper upon the glaciation of the Wyoming and Lackawanna valley.

-The destructive effects of poisoning by phosphorus are narrated in a paper read at a recent

meeting of the Ohio state medical society by a physician whose practice has been large in one of the most extensive match-factories of that state. He finds that the head of each match contains about a seventieth of a grain of phosphorus, and that the injurious results of the process are most marked among those who work in the dipping and packing rooms. The affection is a disease of the bones of the jaw known as necrosis. In some it appears within two years after they enter the factory; in others its appearance is more delayed. Operatives with unsound teeth are the most susceptible. He recommends that only persons possessing sound teeth be employed in these two rooms; that thorough ventilation be provided in all parts of the factories; that the operatives be not permitted to eat their meals within the factory or with soiled hands; and, finally, that mouthwashes of the alkaline carbonates be freely used.

- O. P. Jenkins was elected, June 23, professor of biology, and curator of the museum at DePauw university, Greencastle, Ind.

-The Sanitarian records an instance of flies acting as sanitary inspectors. In one of the rooms of a residence in an eastern city, offensive odors were detected, but their exact source could not be located. The carpets were raised, and a carpenter engaged to take up the entire floor. At this moment a friend who chanced to come in, suggested that an appeal be made to the instinct of the fly. Two blue-bottles were brought from a neighboring stable, and the doors and windows of the room closed. The flies soon settled upon one of the cracks in the floor, and, when the boards were raised at this point, a decomposed rat was found.

The Japanese disease beri-beri, or kakké, is now regarded as a contagious disease, having for its cause a microbe. The infection enters through the intestinal canal, and locates itself at this part of the economy.

LETTERS TO THE EDITOR. *Correspondents are requested to be as brief as possible. The writer's name is in all cases required as proof of good faith.

The flight of the flying-fish.

THE question, among naturalists with whom I have been associated, as to whether or not the flying-fish flaps its wings during its flight, was at first a great surprise to me. My years of sea-service, without hearing a single doubt upon this point, had been exclusively among seafaring men, who are generally positive naturalists seldom are. Nevertheless, association with the former teaches one that their opinion " on a subject is, as a rule, a confirmed belief. In the region of the Cape de Verde Islands, where a very large species of flying-fish is abundant, it is easy to observe the beating of the creature's wings;

but on our own coast, where the fish-and wingsare small, the vibration is so rapid, that, at the usual distance, one cannot well distinguish the motion.

Viewing the question from an engineering standpoint, the problem resolves itself into a simple calculation, the only element of error being in the correctness of observation: for the flight of the fish can only be observed from the deck of a vessel, and the direction of the creature's flight must, at best, be an approximation. The mean of a large number of observations, however, should give a result very close to the truth. Though the flying-fish usually starts directly to windward, it seldom continues in that direction; and, because of this erratic flight, the observation is still more difficult.

The opinion of the naturalists was that the creature projected itself out of the water with great velocity,

sent a greater projected area of wing to the direction of its flight, and therefore its motion would be retarded in a greater ratio than that of a fired projectile having a constant plane of resistance. Artillerists, both on land and sea, are satisfied that they can distinguish the retardation of a cannon-shot: indeed, I doubt if one can be found who would question it; and yet seafaring men are positive the flight of flying-fish is uniform.

A school of flying-fish will keep together in the air quite as well as a flock of ducks. As nearly as one can judge from looking at them, they move at the same velocity. Now, if they continue to move at equal velocity, and do not flap their wings, it follows that they must have projected themselves from the water with equal velocity, and that there must be a constant ratio between the area of their wings and

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The writer was fortunate enough to observe a flying-fish (on the 9th of April, 1886) moving in a direction apparently parallel to that of the ship, and with equal velocity. By means of a Casella anemometer the velocity of the wind across the ship's deck was found to be 13.6 feet per second, and its direction was 20 degrees from ahead.

Referring to fig. 2, b represents the ship; c, the fish; and a, the angle of the wind. The true velocity of the fish through the air was then 13.6 X cos a = 12.78 feet per second.

Let us take, for example, a specimen whose wings and weights would be a mean between the three specimens recorded.


Let A represent the area of its wings in square feet 1750.1234; V, its velocity in feet per second 12.78; A', the projected area of the wings; W, the weight of a cubic foot of air in pounds = 0.075.

In experiments with flying-machines (R. C. Buel, in Appleton's Cyclopaedia of mechanics, vol. i. P. 53), it has been ascertained that an angle of 54° 10" is the most advantageous angle at which the vanes can be placed (these vanes are similar to the wing-fins of a flying-fish). Therefore A' = A X sin 54° 10" = of a square foot, nearly.

V2 A' W

The force with which the air will be pressed downward, or, what is equivalent, the lifting-power of these wings moving at V velocity, will be Substituting the numericals above recorded, we (12.78)2x0.1×0.075-0.0190507 pounds, or about


0.019 0.177




the weight of the fish in question. The method of catching flying-fish on board the Albatross affords a means of observing some of their motions. When our submarine (Edison's) lamp is lowered a few inches below the surface of the water, these fish often approach it gradually. On such occasions they invariably have their pectorals and ventrals extended, but do not appear to use them as organs of locomotion on becoming alarmed, they close these fins, and dart forward suddenly. The brilliancy of the electric light, no doubt, dazzles their eyes greatly, for they do not appear to see objects near them, and, when alarmed by the splash of the scoop-net, dart right forward by use of the caudal fin. Mr. Nye, quickly perceiving this habit, takes advantage of it by plunging the net directly in front of the fish, which be almost invariably catches. On one occasion a fish turned in its flight, and projected itself several feet vertically into the air, very close to the side of the ship, working its wings vigorously, which was distinctly seen by several people on deck. G. W. BAIRD.

Passed Assistant Engineer, U.S.N.

Washington, June 24.

An Indian snake-dance.

I have received a clipping from the New York Commercial advertiser containing a letter from a Mr. Trumble in reference to the article on the snakedance' of the Moki Indians of Arizona (Science, vii. June 4). Mr. Trumble mentions the occurrence of similar performances among several Central and South American tribes, and discusses at some length the antidotes used. This feature was only touched upon in my paper for the reason that Dr. H. C. Yarrow of the army, who attended the dance at Wolpi for the special purpose of identifying the species of

snakes used, and of determining whether they had been rendered innocuous, was present at the reading of the paper, and was kind enough to discuss it at some length. Perhaps the interest in the question would justify a few remarks on that phase of the subject. Dr. Yarrow identified four species of snakes, only one of which, however, was poisonous,

the spotted rattlesnake, or Crotalus confluentus. He descended into the snake kiva on the eve of the dance, and there examined the snakes which were to be used on the morrow. At his request a large rattlesnake, selected by himself, was held up for his examination by one of the Indians, and, upon prying its mouth open, he found the fangs intact and of large size. I may add, that, at the conclusion of the 1883 snake-dance, two rattlesnakes were They captured, and sent to the national museum. were examined soon after their arrival by Dr. S. Weir Mitchell of Philadelphia, who found them in perfect order: their fangs had not been disturbed, and the poison-sacks were intact and full of venom.

The snakes used in the dance undergo a very complicated course of treatment in the kiva where they are confined prior to their appearance in public. They are washed repeatedly in various kinds of 'medicine-water,' and are frequently handled or stroked with a downward, squeezing movement of the hand. Whether such treatment prolonged over a period of five or six days is sufficient to render innocuous a robust rattlesnake, is an open question. Both Captain Bourke in his book, and Dr. Yarrow in his remarks, mention seeing a large rattlesnake brought in from the fields on the day of the dance. These, at least, must have been capable of inflicting fatal wounds.

The Indians have the greatest confidence in the means they use to secure immunity. Dr. Yarrow, in an interview he had with the high priest soon after the dance, showed the old man a hypodermic syringe and a solution of permanganate of potassium, which he had brought along to use in case of necessity, and explained to him their use. The old man replied, "No doubt my brother's medicine is good, but we are quite satisfied with our own." The performers are very seldom bitten: I observed but one instance at Wolpi, none at Mashongnavi. Others, however, record two other instances at Wolpi, which escaped my attention: in both of these cases the bite was inflicted by non-venomous serpents. As the number of snakes used at that dance was about eighty, this is not a very high percentage. I am of the opinion that the Mokis rely on the previous treatment of the snakes, on their charms and incantations, rather than on any after-treatment of themselves. As Dr. Yarrow remarked, a snake which had been repeatedly handled, and had discovered that no injury was intended, would become comparatively tame, and this would account for the behavior of the snakes during the dance. In the hands of the dancers, they seem numbed and lifeless, and it was only when dropped rudely on the ground from the mouths of the dancers that they showed any disposition to fight.

The knowledge of the composition of the liquids used by the Mokis is confined to one man, a high priest; even the members of the order are ignorant of it but, to provide against the loss of the secret, the knowledge is shared with an old woman of the tribe. The high priest keeps this knowledge to himself until he is, or thinks he is, on his death-bed;

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