The

average appropriation for many years past. report also speaks of the advance toward completion of the resurvey of New York bay and harbor, to the studies of ice formation and movement in Delaware river and bay, to the observation of currents in the Gulf Stream, and to the near approach of the transcontinental triangulations, which will form a geodetic connection between the work on the Atlantic and that on the Pacific.

-The remarkable regularity in the recurrence of climatic conditions, as well as the small variation in the weather on a subtropical island, is illustrated in the following table of maximum and minimum temperatures in the summer months of 1885 and 1886, at Nassau, Bahamas, clipped from a paper published there.

Thunder-storms seem unpleasantly frequent. In 1885 there was lightning with rain every two days from May to September, with a violent storm about once a week; in 1886, lightning and rain were as frequent, but severe storms were reduced to only once a fortnight. The general absence of lightning-rods makes these storms a rather dangerous element in the summer weather of Nassau.

An interesting case is reported to have occurred at Rising Sun, Ind. According to the accounts, a man named Seward, a farm-laborer, aged twenty-eight years, became sick about six months ago. At first there was nothing especially noteworthy about his sickness except that he was easily tired. Although a man of unusual strength, two hours of labor completely prostrated him. This increased, until, after two months, he was totally unfit for work, and at the same time his skin became changed in color. In health a blonde, with gray eyes, his face became ash-color, and then darker and darker, until, at the time of his death, it was like that of a negro. The neck, shoulders, hands, fore-arms, and afterwards other portions of the body, became similarly affected. The disease above referred to was undoubtedly what is known as Addison's disease.

In 1855 Dr.

Thomas Addison first described it. He regarded it as connected with disease of the supra-renal capsules, and since his day there has been but little more learned about its causation than Addison himself knew. The deposit of pigment in the lowest layers of the epithelium is the outward manifestation of the affection, though why it should be so deposited is not known. The disease occurs in adult life, very seldom in childhood or in old age. Males and laborers are usually the patients. Although it may last for many years, it is almost invariably fatal. Dr. Greenhow has devoted especial attention to this disease, and treats of it in the Croonian lectures on Addison's disease,' published in the Lancet in 1875. In vol. iii. of System of medicine by American authors.' is an article on the subject, written by Professor Osler, to which we would refer those who desire more particulars of this remarkable disease.

- The next number of the Proceedings of the American society for psychical research is to be issued as soon as sufficient material is collected. The council is anxious to obtain, so far as may be possible, the co-operation of all members and associate members of the society, in the preparation of this number. All members are therefore earnestly requested to report any experiences or observations which they may have collected on any subjects falling within the range of the society's work. Edw. G. Gardiner, 12 Otis Place, Boston, Mass., is the secretary.

- A curious feature of the weather, described in the Ohio meteorological bureau report for September last, is the damage caused by the lightning in a violent storm on the 23d of the month. The rain was very heavy at certain stations, Sidney reporting 5.57 inches in twenty-four hours. At New Bremen the storm began at 8 P.M. on the 22d, with high wind and hail-stones. From 2 to 3 A.M. on the next morning there was a continuous blaze of lightning. As the storm moved eastward, it entered a region cf oil-wells, where derricks and tanks were struck, and large quantities of oil set on fire. At Lima the lightning struck a derrick, and ran thence by a pipe-line to a tank thirty rods distant, where it fired a thousand barrels of oil. Old oil-men said they had never experienced such storms in the Pennsylvania oilfields, and were anxious to know if they were common in Ohio. The Ohio monthly report now occupies fifty-eight pages, and presents the records of thirty-seven stations in much detail.

and tilted and folded slates, worn down smooth, close to its base level of erosion, and then recently unevenly elevated in three great blocks. Every block is slightly tilted to the westward, and separated from its neighbor by a fault with bold face, falling steeply to the east. Longitudinal valleys lately occupied by lakes lie between the eastern face of one block and the long western slope of the next. During and since the uplift, streams flowing westward down the longer slopes have cut deep cañons. The date of the faulting is in great part later than the lavas of Lassen's Peak and thereabouts, and it is at least very likely that the dislocation is still in progress. The limestone beds of the region are considered of carboniferous age by previous observers, but a large portion of the auriferous slate series is thought to be of older origin.

A recent supplement (No. 83) to Petermann's Mittheilungen contains an elaborate account by Dr. Berndt, of the effects of the foehn the hot, dry wind of the Swiss valleys — on organic and inorganic nature. The memoir is prefaced by a good description of the wind itself: it is illustrated by a map showing the valleys, south as well as north of the divide, that are most frequented by it, and also by two weather-charts for the foehn of Feb. 20, 1879, demonstrating its relation to a cyclonic area of low pressure that crossed Europe from France over central Germany on that day. The body of the work is concerned with the action of the foehn on the mountain snow, and the floods thereby produced in the valleys, with its relation to rock-weathering and consequently to topography, and to its effects on plants, animals, and men. The danger of village fires is great during the prevalence of the hot wind, and extra watchmen are employed then. After the town of Glarus was thus burned in 1861, even smoking was prohibited outdoors and in the public streets during the blowing of the foehn.

- Dr. Forel, the distinguished Swiss entomologist, has recently published an account of experiments designed to ascertain whether the perception of the ultra-violet rays of the spectrum by ants took place by means of their eyes, or as a photo-chemical action on the skin. By varnishing the eyes of some ants, it became evident that the main impression was a visual one: such ants did not exhibit the preference for darkness above ultra-violet light which normal ants showed. This does not absolutely exclude any action on the skin, but makes it improbable. It is interesting to note that the blind are unable to judge of the amount of light in a room if care is taken to exclude the effects of heat and other indications.

The college building in Charleston was so much injured by the recent earthquake that they have been obliged to pull down entirely the two wings, equivalent to nearly half the space occupied by the whole building. Half of the specimens in the museum of natural history, and all the physical and chemical apparatus. have been removed, and crowded into the remaining por tion, which has also to serve for lecture and recitation rooms. The private library and collection of Mollusca and Crustacea belonging to Prof. L. R. Gibbes, and probably the most valuable in the south, were also in one of the wings, and of course had to be removed. Our naturalists will have great sympathy for those upon whom this unlooked-for labor has fallen, but will be glad that the collections are uninjured.

A very interesting communication to the Medical news has been made by Dr. F. Peyre Porcher of Charleston, on the influence of the recent earthquake shocks in that city upon the health of the inhabitants. In addition to the natural alarm and fright which were quite universal, some persons were attacked with nausea and vomiting, which recurred or persisted in several cases for days. Two gentlemen on the islands eighty miles from Charleston bad their eyes filled with tears not to be repressed, but not caused by alarm, or fears for their personal safety, for the danger there was not imminent. Many persons experienced decidedly electrical disturbances, which were repeated upon the successive recurrence of the shocks. These were generally tingling, pricking sensations, like needles and pins,' affecting the lower extremities. One gentleman was completely relieved of his rheumatism; another, who for months was nervous, depressed, and entirely unable to attend to business, regained his former activity and energy. Several cases of mental disturbance, owing to anxiety and prolonged loss of rest, some of them persistent, occurred among Dr. Porcher's patients.

We had occasion in a recent number of Science to refer to a remarkable case in which the breath of an individual, or rather the eructations from his stomach, took fire when brought in contact with a lighted match. This case, which was reported in the Medical record, has called forth communications from physicians by which it would appear that the phenomenon is not such a rare one as was at first supposed. In one case of disordered digestion the patient emitted inflammable gas from the mouth, which, upon analysis, was found to be largely composed of marsh gas. In another case the gas was sulphuretted bydrogen. A case is reported in the

British medical journal, in which, while blowing out a match, the patient's breath caught fire with a noise like the report of a pistol, which was loud enough to awaken his wife. One evening, while a confirmed dyspeptic was lighting his pipe, an eructation of gas from his stomach occurred, and the ignited gas burned his mustache and lips. In Ewald's book on indigestion, the analysis of the gas in one of these cases was, carbonic acid, 20.57; hydrogen, 20.57; carburetted hydrogen, 10.75; oxygen, 6.72: nitrogen, 41.38; sulphuretted hydrogen, a trace. The origin of these gases is undoubtedly the undigested food, which in these cases undergoes decomposition.

- Dr. Gilles de la Tourette finds that the average step of men is twenty-five inches; for women, twenty inches. The step with the right foot is somewhat longer than that with the left. The feet are separated laterally in walking about four and one-half inches in men, and five in women.

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.

Cremona's Projective geometry.

YOUR review of this work does scant justice, I think, to one of the most valuable text-books recently published. We have a multitude of elementary books in all branches of science; but why most of them are printed, there seems to be no reason, unless it be the reason why cheap razors are made. For my own part, I am thankful when we get a book such as Professor Cremona has given us, a book so well designed to give the student more general views of geometry. ASAPH HALL.

Washington, D.C., Dec. 28.

Pleuro-pneumonia.

Referring to Mr. Butler's communication and your editorial remarks on p. 587, it may be of interest to put on record the fact that horses have suffered quite extensively, particularly in Indiana and Missouri, from what Dr. Salmon has decided to be vermicular or verminous bronchitis. He has fully treated of this disease, and illustrated the Strongyli which induce it in calves and lambs, in the veterinary part of the 'Agricultural report for 1885.' That producing the disease in horses seems to be Strongylus micrurus mepls, which is carefully figured on plate V., and described on p. 557. It is an elongate, threadlike worm from an inch and a half to two inches in length; and the point that I wish to put on record is that these Strongyli have very generally been supposed to have some connection with the narrow elongate eggs of Orchelimum glaberrimum. The eggs of this species are inserted in the pith of a number of different plants, and are particularly abundant in stalks of corn-tassels. The punctures were figured in my Fifth report on the insects of Missouri,' and again referred to in bulletin

6, U. S. fish commission The bronchial disease which has been so prevalent and fatal to horses has been quite generally associated with these eggs, the supposition being that the horses became diseased by eating the corn tassels and stalks. The Orchelimum eggs have been received from about a dozen different correspondents, all of them independently making the same suggestion as to their connection with the bronchial worms, a rather remarkable instance of a prevalent and popular error arising from an imperfect knowledge of natural science. C. V. RILEY. Washington, D.C., Dec. 27.

Stereoscopic vision.

I would like to inquire of the readers of Science if it is generally known to be possible — and if, indeed, it is possible to all persons to obtain a complete stereoscopic effect in viewing a single picture, and without a glass or other instrumental aid.

I have for several years been in the habit of practising a method in looking at photographs or good engravings, which, with me, makes the illusion perfect, and the objects pictured seem to stand out in full relief like the real objects.

In consists simply in entirely closing one eye, and shutting the other as nearly as possible, while admitting just sufficient light to afford a distinct, or at first rather dim, view of the picture. It is necessary first, however, to see that the picture is placed in a light corresponding as accurately as possible in direction with that in which the objects are represented in the picture: for example, if the scene is shown as lighted from the left, let the picture be so held that the actual illumination is from the left, and exactly at the same angle. An incongruity in this respect will spoil the result entirely. A little time is usually required to realize the full effect, and probably many persons unaccustomed to the experiment will need to exercise more patience at first than after some practice.

It is found, too, that a picture presenting strong lights and shades, as of photographs of objects in the direct sunlight, or engravings of the same character, produces the effect most readily. Take, for example, the engravings representing highly magnified views of the scenery on the surface of the moon, such as those illustrating Professor Langley's article The new astronomy,' in the Century. After looking at one of those in that manner for a few moments, the parts represented as elevations appear to rise from the paper; and, indeed, the flat surface disappears altogether, as well as the inky blackness of the shadows, and both elevations and depressions appear in startling reality.

The lights and shadows appear to be merely the illuminated and unilluminated portions of the same uniformly colored substance, showing it distinctly carved in all the reality of the forms intended to be indicated. It seems as if one could closely estimate the actual heights of the elevations, and the lengths of the shadows, and the precise position of the source of light.

The illusion once perfected, it may be retained while opening the eye a little, thus gaining a clearer view; but, carrying this a little too far, the scene at once flattens out' again, and becomes a mere lifeless black-and-white representation of the outlines, producing nothing of the impression of reality of contour the landscape is gone.

As far as I am aware, this simple method is not generally known or thought of; nevertheless I am inclined to the belief that it would become easy to most persons after a little practice, and it is certainly very convenient, and greatly enhances the pleasure of viewing the many fine engravings almost everywhere to be seen. W. H. PRATT. Davenport, Io., Dec. 14.

Laws against quacks.

I notice in your notes on the laws regulating the practice of medicine and surgery an omission to call attention to the fact that a bill (senate, 485) passed the senate last year, and would have passed the assembly but for the late date of its introduction, whereby it failed to be reached on the calendar. That bill embodied the points of agreement of those practitioners of medicine who have a legal status. It was based upon the bills introduced by the Medical society of the state of New York, so far as they were not concerned with the formation of a board of medical examiners. The State homoeopathic society has directed its legislative committee to favor this bill if again introduced, as it probably will be. I do not think that either of the judges you name would consider the construction of the registration law adopted by the Medical society of the county of New York as absurd; nor would they differ in opinion from the judges before whom that construction has been maintained.

You will admit, I think, -as frankly as you admitted that the society was justified in the prosecution that elicited your comments, that it is reasonable to require registration of every physician in a county who regularly practises or resides therein. No registered physician has been prosecuted for a consultation or occasional act of practice in a county wherein he was not registered. But the bill in question specifically meets your criticism, and, if introduced again, will be made even clearer on this point There is an opportunity at the next session of the legislature to codify the various acts restricting medical practice into a simple statute, and fair criticism of the bill in question will materially aid the purging of the statutebook of the present clumsy enactments.

New York, Dec. 21.

W. A. PURRINGTON.

The Panama canal.

The article with the above title, from the pen of M. de Lesseps, copied by you in Dec. 3 issue from The Scottish geographical magazine for November, contains some errors both of fact and of inference.

Commercially the needs for and uses of the canal are misstated and overestimated. Trade must follow certain routes, governed by the earth's form and dimensions, and by the winds that blow or do not blow. For fear of the calm belt in Gulf of Mexico, the captain of a big ship, loaded with guano or nitrate of soda, would rather face the gales off Cape Horn. Because of the 'trades,' sailing ships from India and Australia would still go home via Cape of Good Hope. I have yet to meet a captain who would not elect Cape of Good Hope rather than Panama if loaded at a port even as far cast as Philippines. A sailing-ship bound from San Francisco to Liverpool would think twice before she paid any thing to be put into the calms in land-locked water off

Colon. Many captains have told me they would go on around the Cape Horn. Many cargoes are put on to sailing-ships, because they will be longer at sea than if sent per steam. It is no uncommon thing that a sailing-ship gets the same, and even more, freight than a steamer, because of the exigencies of the shipper or the condition of the market for merchandise. Hence the assumption that any of his '2' (p. 519), or that all of '1' or '3,' would seek Panama, is unfounded. A fair estimate, granting the correctness of his figures, would throw out 2,' and halve '1' and 3,' and leave, say, rising 2,000,000 tons per annum. In the table of distances, same page, London to Sydney, Havre to Sydney, he conveniently forgets that that traffic would use Suez rather than Panama. I fancy it is not generally known that the entire traffic of Suez is steam. There has never been an American merchantman through Suez, nor a sailing-ship of any nationality. The few sailers that have passed through were towed not only through Suez, but the entire distance to and from port of departure (Bombay) and destination (Malta). Practically the entire traffic on Suez is steam

But M. de Lesseps does not refer to the most important factor in the problem. The evolution of the marine engine is still progressing. Steamers of moderate size and speed already approximate the expenses of sailers, not counting the further saving in interest on plant by reason of more frequent 'turns ;' i.e., though a steamer may cost more than sailer, the former makes more voyages in a year, i.e., earns more freights. Before the Panama canal is finished, I doubt not such progress will have been made in compounding engines and in expansion of steam, that few new sailers will thereafter be built. The carrying-trade of the world will be done by steamers, just as the passenger trade has passed into their hands. Soon, as nations reckon life, sail will be limited to cruising for pleasure, fish or whale, or scientific research: even these will have steam power to go and come to place of resort. This change might and probably would throw the traffic of west coast America with east coast America and Europe into Panama canal; but Australia and India with Europe and America, never. FRANK GOODWIN.

Framingham, Mass., Dec. 13.

What was the rose of Sharon ?

In Science for May 14 (vii. No. 171) is an article headed What was the rose of Sharon?' Though not familiar with either former or recent discussions of the question, I am interested in recalling an observation of my own while riding over the plain of Sharon on the road from Jaffa to Ramleh. It was about the middle of the afternoon, Feb. 18, 1859. The dark soil was for a considerable distance half covered with broad patches of bright red flowers. ' Roses of Sharon!' some one exclaimed. I forget whether it was the United States consul from Beirut or some one else of our party. As my impression now is, several persons who were likely to know concurred in saying that these flowers were commonly so called in that region. The flower which I gathered and pressed was afterwards identified by an American scholar as Anemone coronaria of Sibthorp's 'Flora Graeca.' The color of the dried petals is now a dark maroon. FISK P. BREWER.

Grinnell, Io., Dec. 18.

FRIDAY, DECEMBER 31, 1886.

SEACOAST DEFENCES.

THE two excellent and valuable articles on seacoast defences which have been placed before the public within a few days of each other - the one by Lieut. Eugene Griffin of the corps of engineers, in the Journal of the military service institution, and the other by Capt. F. V. Greene of the engineers, in Scribner's magazine - should suffice to convince the most devoted advocate of a 'peace policy,' and the most economical of legislators, that something should be done by the authorities, and that speedily, as a mere matter of insurance if nothing more, to protect our defenceless seaports. Lieutenant Griffin's paper is more technical than Captain Greene's, as might be supposed from the fact of its being published in a magazine devoted exclusively to military interests; but while Captain Greene's article is popular, it is not superficial, and by a comparison of the two the intelligent reader can gain an excellent insight into the subject. Lieutenant Griffin summarizes the arguments against coast defences under three heads 1. The navy should constitute our defence; 2. Torpedoes alone suffice to close any channel; 3. Earthen batteries of sufficient strength can be hastily thrown up in case of war. He then answers these objections by showing that the office of the navy is not defensive, but offensive: it should protect our commerce on the high seas, and injure that of our enemies. Moreover, fixed guns on land have many advantages over guns on floating supports. The second argument proceeds from entire ignorance of the nature and object of torpedoes. They have been introduced to offset the advantages gained by the attacking party in the invention of the screw-propeller. Their function is to harass an enemy's ships, and prevent them from running by batteries. Instead of being a substitute for fortifications, torpedoes presuppose the latter. The plea that earthworks can be thrown up as rapidly as need be, is shown to be equally flimsy. In winter no suitable earthworks could be thrown up at all in our northern states. And supposing the largest available force to work day and night, it would take more than a week to construct the seventyfoot parapet. What this means is evident when we remember that Bermuda is only seventy-one hours' steaming from Savannah, sixty-six hours

from Charleston, and fifty-eight hours from New York; that a British fleet could get from Halifax to Portland in thirty-one hours, and to Boston in five hours more, or from Vancouver to San Francisco in ninety-six hours. Similarly a Spanish fleet at Havana is within forty-five hours of New Orleans. Then, as Lieutenant Griffin points out, the modern theory is to make war sudden, sharp, and decisive, and to make the defeated party pay all the expenses. The billion of dollars which Germany exacted from France in 1871 would be but a fraction of what we should have to pay to any hostile power that had our great seaports at its mercy.

We have on the Atlantic and Pacific and lake coasts "a series of great cities containing an aggregate population of more than five million souls, and destructible property which is carried on the assessors' books with a valuation of $4,000,000,000 (and which probably has an actual value of nearly twice as much), yielding annually a product in manufactured goods alone valued at over one thousand million dollars." Captain Greene shows that every man, woman, and child of this great population, and every dollar of this vast accumulation of wealth, is in danger of destruction by a hostile fleet. As he puts it, the problem is one of national insurance on life and property. Now, the usual annual premium on policies of insurance on life or property, with good risks, is from one to one and one-half per cent. In Captain Greene's judgment, less than half that percentage, computed on the sum total of property exposed, — say, $20,000,000,- expended annually for six years, would give us a complete system of insurance; that is, it would suffice to erect harbor defences stronger than any ships which could be brought against them, or, with an expenditure of $10,000,000 annually for six years, - a sum which is only about three per cent of our annual appropriations for the support of the government, fully three-fourths of the lives and property on our coasts could be placed out of danger.

To these considerations Lieutenant Griffin adds the teaching of history, which is that the surest way to avoid war, with all its attendant ravages and losses, is by so thorough a preparation that no weak point is exposed to an enemy's attack, and no temptation is offered to his cupidity.

Besides dealing with the general question in the way indicated, both Captain Greene and Lieutenant Griffin discuss the various problems presented