It is well known in various countries that fishes swim up to a boat on a stream if a light is displayed on board.

An interesting spectacle is produced if a candle, or better still an electric glow lamp is brought near the glass sides of an aquarium. Fishes, aquatic larvæ and mullusca swim up and seek to come as near as possible to the light.

Numbers of nocturnal insects are attracted by flame. Moths, gnats, crane-flies and many other diptera are noted for their propensity to commit suicide in our lamps and candles. Many of the smaller moths are found sitting on the glasses or the iron frame work of street-lamps. I have known an old lady made ill with fright because a death's-head (Acherontia atropos) had flown against her candle and put it out.

But we must now giance at the main question, that is, the meaning of the behavior of nocturnal animals in presence of a light. The alarm of many species is not hard to understand. A bright light is a phenomenon which does not fall within the limits of their experience and seems to them, therefore something to be avoided. But to see nocturnal, abysmal or cavedwelling species flocking to a light is perplexing.

⚫ It has been suggested that the moth thinks the flame an outlet through which it may escape. But why should it seek to escape from a condition which to it is as normal as is sunlight to the butterfly or to the bee? It has again been suggested that nocturnal insects and fishes are able to preceive the faint phosphorescent light apparently given off by many flowers, and by aquatic worms, etc. Hence the moth rushes to the lamp mistaking it for a flower. On coming nearer he is bewildered by the intensity of the light and loses his head." This same supposition explains why mosquitoes are less attracted by a lamp than are most other insects. They are not accustomed to find their food in phosphorescent flowers, hence the lamp has to them little attraction. True, this hypothesis fails to show why birds should dash themselves against the windows of a lighthouse. Their normal food is not phosphorescent. Nor, to our knowledge, are their eyes capable of perceiving a faint phosphorescent light.

Probably no single hypothesis will meet all the cases of the attraction of animals to light. J. W. SLATER. London, England.

The Aurora.

The contradiction in certain statements of mine with reference to the possibility of tracing the relation of the aurora to disturbances upon a particular part of the sun in certain years which Professor Ashe thinks he has detected and which he puts into italics at page 9 of Science for July 7 amounts to simply this: In one sentence which he quotes I am giving the reason why the relation in question comes out distinctly in years of minimum, namely, because the disturbances are well separated from each other, and, taking 1879 as an example, show by a table that this was the case in that year, in which both auroras and sunspots were so very few that the numbers to be employed were so extremely small that it might justly be doubted whether they show anything, and yet, in spite of this disadvantage, namely, the smallness of the numbers, the relation was plainly apparent. In another sentence, referring to the matter from this point of view, namely, the size of the numbers to be employed, I state that in 1880 the relation in this respect would be much more distinct, this also being a year of comparative minimum in which the disturbances were well separated from each other, so that the conclusion with reference to this year contained in the sentence which Professor Asche quotes would be fully justified, i.e., "the numbers would be larger and the relation in every way more distinct." The only reason for the publication of the table for 1879 was to show what would appear in the year in which we might suppose the relation exceptionally difficult to trace and yet in which it was distinctly apparent in spite of the smallness of the numbers. It was simply picking out the worst possible case, as we would naturally suppose, instead of the best possible case, and it is to its discussion that the sentences which Professor Ashe quotes, refer. M. A. VEEDER. Lyons, N. Y., July 13.

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Natural Selection at Fault.

I AM truly sorry if, in my remarks on this subject, I have failed to make myself understood. As regards the common cat, I have seen not merely half-grown kittens, but middle-aged mousers, play with their booty and lose it.

The idea of this practice having the object of cultivating agility seems to me exceedingly far-fetched.

I have not sought to account for the cackle of hens, but have merely pointed out the undeniable fact that it is very liable to attract the attention of any ovivorous bird or beast to the probable presence of an egg.

The rarity in man of the power to erect the ear, or to turn it so as to catch any faint sound-waves has been repeatedly noticed, as also the fact that it does not collect all the impinging sound-waves into the orifice of the ear. My only merit, or demerit (?), has been to cite the abated condition of the ear-muscles as an instance of natural selection at fault. The ear is probably in a state of transition, but in what direction? J. W. SLATER.

London, England, April, 25.

The Habitat and the Diet of the Lepidoptera.

A FEW lepidopterous species select in different countries widely different habitats and food plants. Thus Papilio machaon, the most common European species of papilio, is confined in England to the fenny districts of Cambridgeshire, and occasionally extends to small portions of the adjoining counties. What with the greediness of collectors for "British specimens" of any remarkable insects, and with the drainage of the fields, it is feared that this species will soon be extirpated. The caterpillar of this species, in England, feeds on swamp plants.

In central Europe Papilio machaon is fairly abundant on the dry, gravelly hills and certain parts of lower Silesia, Bohemia and Saxony, the very opposite in their character to the fields of Cambridgeshire. The larva in Silesia and Bohemia feeds frequently on the mountain ash.

The three hawk moths, Chanocampa celerio, Ch. elpenar and Ch. porcellus, on the European continent, feed chiefly upon the vine. But in England they feed on bed straw, willow herb and sometimes on the fuchsia. I have in vain tried to induce larvæ of elpenar or porcellus to feed on vine leaves, probably if the ova had been placed upon vine leaves the young larvæ would have not refused this, their normal food. J. W. SLATER. London.

Beaver Creek Meteorite.

Between the hours of 3 and 4 P. M. on the 26th of May last, a meteorite was heard by many persons, and three of the fragments were seen to fall near Beaver Creek, West Kootenai District, B. C., a few miles north of the United States boundary.

The two smaller of these fragments, weighing perhaps 5 to 6 pounds in all, were picked up at once; the larger one, weighing about 25 pounds, was not found until the next morning. It made a hole in the wet earth about three feet deep, two feet in soil and one foot in hard pan. The direction of the hole was south 60° east, true meridian, and at an angle of 58° with the horizon. Fresh earth was scattered about the hole in all directions, but farthest (10 feet) in the direction from which the stone came.

On the 6th inst. I saw and purchased this stone from Mr. James Hislop, a civil engineer, who found it and brought it to Washington.

It is a typical aërolite of very pronounced chondritic structure. It is completely coated with the usual black crust except at one end, where about three pounds have been broken off and scattered, like the two smaller stones, mostly among mere curiosity hunters. The mass now weighs 22 pounds. measures 6 × 7 × 9 inches, and approaches in shape an acute octahedron.

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Dr.American Gallinae in the flesh for the study of HE undersigned desires specimens of North their pterylosis. These species are especially desired: Colinus riogwayi, cyrtonyx montezumae, deudragapus franklini, lagopus welchi, tympanuchus cupido and pedivecetes phasianellus. Any persons having alcoholic specimens which they are willing to loan or who can obtain specimens of any of the above are requested to communicate with Hubert Lyman Clark, 3922 Fifth Avenue, Pittsburgh, Pa.

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NEW METHOD OF PROTECTING BUILDINGS FROM LIGHTNING. SPARE THE ROD AND SPOIL THE HOUSE! Lightning Destroys. Shall it be Your House or a Pound of Copper?

PROTECTION FROM LIGHTNING.

What is the Problem?

IN seeking a means of protection from lightning-discharges, we have in view two objects, the one the prevention of damage to buildings, and the other the prevention of injury to life. In order to destroy a building in whole or in part, It is necessary that work should be done; that is, as physicists express it, energy is required. Just before the lightning-discharge takes place, the energy capable of doing the damage which we seek to prevent exists in the column of air extending from the cloud to the earth in some form that makes it capable of appearing as what we call electricity. We will therefore call it electrical energy. What this electrical energy is, it is not necessary for us to consider in this place; but that it exists there can be no doubt, as it manifests itself in the destruction of buildings. The problem that we have to deal with, therefore, is the conversion of this energy into some other form, and the accomplishment of this in such a way as shall result in the least injury to property and life.

Why Have the Old Rods Failed?

When lightning-rods were first proposed, the science of energetics was entirely undeveloped; that is to say, in the middle of the last century scientific men had not come to recognize the fact that the different forms of energy heat, electricity, mechanical power, etc.- were convertible one into the other, and that each could produce just so much of each of the other forms, and no more. The doctrine of the conservation and correlation of energy was first clearly worked out in the early part of this century. There were, however, some facts known in regard to electricity a hundred and forty years ago; and among these were the attracting power of points for an electric spark, and the conducting power of metals. Lightning-rods were therefore introduced with the idea that the electricity existing in the lightning-discharge could be conveyed around the building which it was proposed to protect, and that the building would thus be saved.

The question as to dissipation of the energy involved was entirely ignored, naturally; and from that time to this, in spite of the best endeavors of those interested, lightning-rods constructed in accordance with Franklin's principle have not furnished satisfactory protection. The reason for this is apparent when it is considered that the electrical energy existing in the atmosphere before the discharge, or, more exactly, in the column of dielectric from the cloud to the earth, above referred to, reaches its maximum value on the surface of the conductors that chance to be within the column of dielectric; so that the greatest display of energy will be on the surface of the very lightningrods that were meant to protect, and damage results, as so often proves to be the case.

It will be understood, of course, that this display of energy on the surface of the old lightning-rods is aided by their being more or less insulated from the earth, but in any event the very existence of such a mass of metal as an old lightning-rod can only tend to produce a disastrous dissipation of electrical energy upon its surface," to draw the lightning," as it is so commonly put.

Is there a Better Means of Protection?

Having cleared our minds, therefore, of any idea of conducting electricity, and keeping clearly in view the fact that in providing protection against lightning we must furnish some means by which the electrical energy may be harmlessly dissipated, the question arises, "Can an improved form be given to the rod so that it shall aid in this dissipation?"

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As the electrical energy involved manifests itself on the surface of conductors, the improved rod should be metallic; but, instead of making a large rod, suppose that we make it comparatively small in size, so that the total amount of metal running from the top of the house to some point a little below the foundations shall not exceed one pound. Suppose, again, that we introduce numerous insulating joints in this rod. We shall then have a rod that experience shows will be readily destroyed-will be readily dissipated when a discharge takes place; and it will be evident, that, so far as the electrical energy is consumed in doing this, there will be the less to do other damage. The only point that remains to be proved as to the utility of such a rod is to show that the dissipation of such a conductor does not tend to injure other bodies in its immediate vicinity. On this point I can only say that I have found no case where such a conductor (for instance, a bell wire) has been dissipated, even if resting against a plastered wall, where there has been any material damage done to surrounding objects.

Of course, it is readily understood that such an explosion cannot take place in a confined space without the rupture of the walls (the wire cannot be boarded over); but in every case that I have found recorded this dissipation takes place just as gunpowder burns when spread on a board. The objects against which the conductor rests may be stained, but they are not shattered, I would therefore make clear this distinction between the action of electrical energy when dissipated on the surface of a large conductor and when dissipated on the surface of a comparatively small or easily dissipated conductor. When dissipated on the surface of a large conductor, a conductor so strong as to resist the explosive effect,- damage results to objects around. When dissipated on the surface of a small conductor, the conductor goes, but the other objects around are saved

A Typical Case of the Action of a Small Conductor. Franklin, in a letter to Collinson read before the London Royal Society, Dec. 18, 1755, describing the partial destruction by lightning of a church-tower at Newbury, Mass, wrote, “Near the bell was fixed an iron hammer to strike the hours; and from the tail of the hammer a wire went down through a smali gimlet-hole in the floor that the bell stood upon, and through a second floor in like manner; then horizontally under and near the plastered ceiling of that second floor, till it came near a plastered wall; then down by the side of that wall to a clock, which stood about twenty feet below the bell. The wire was not bigger than a common knitting needle. The spire was split all to piece by the lightning, and the parts flung in all directions over the square in which the church stood, so that nothing remained above the bell. The lightring passed between the hammer and the clock in the above-mentioned wire without hurting either of the floors, or having any effect upon them (except making the gimlet-holes, through which the wire passed, a little bigger), and without hurting the plastered wall, or any part of the building, so far as the aforesaid wire and the pendulum-wire of the clock extended; which latter wire was about the thickness of a goose-quill. From the end of the pendulum, down quite to the ground, the building was exceedingly rent and damaged.. No part of the aforementioned long, small wire, between the clock and the hammer, could be found, except about two inches that hung to the tail of the hammer, and about as much that was fastened to the clock; the rest being exploded, and its particles dissipated in smoke and alr, as gunpowder is by common fire, and had only left a black smutty track on the plastering, three or four inches broad, darkest in the middle, and fainter towards the edges, all along the ceiling, under which it passed, and down the wall." One hundred feet of the Hodges Patent Lightning Dispeller (made under patents of N. D. C. Hodges, Editor of Science) will be mailed, postpald, to any address, on receipt of five dollars ($5).

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