tives were so adjusted that the pupils of the eyes in each case fell upon the same points of the sensitive plate, while in fig. 1 the distance from the line of the eyes to the mouth was made constant.

The result of these different modes of adjustment is apparent in the multiple mouth which disfigures fig. 2, and in the less clear definition of the eyes in fig. 1, in which the component eyes fell upon slightly differing points in the same horizontal line.

The question at once arises, which of these faces, if either, in its general outline and expression, is the true average of the group? In seeking the typical features should we choose fig. 1, and correct the dimness of the eyes, or take fig. 2, and substitute a single mouth in the middle of the blur? As far as I can learn, this question of adjustment and its results has not before been raised. It is, however, a question of importance to all who are interested in composite photography; for only those composites which are made according to the same method of adjustment can be properly compared as types.

In any group of persons not chosen with special reference to facial symmetry, the ratio of the distance between the pupils of the eyes to that between the line of the eyes and the mouth is a variable one; and adjustment to either distance as a constant for the group will give its corresponding and differing composite. Mr. Galton makes the distance from eyes to mouth constant (Inquiries into human faculty,' p. 359). The portraits of American men of science (Science, v. No. 118) seem (from the tendency to multiple mouths and noses, especially noticeable in fig. 1) to have been made, as fig. 2 was, by matching the eyes, though in these cases the beard prevents the prominence of the disfigurement which this adjustment gives in the case of smooth faces.

If a fixed distance between eyes and mouth be taken for adjustment, the composite will have a single distinct mouth, but will differ in form according to the distance chosen; if it be that of the shortest or of the longest face in the group. the composite face will be correspondingly short or long, and the indistinctness of the eyes at a maximum. But if, on the other hand, a component face of average length (i.e., one in which the ratio of the distance between the pupils of the eyes to that between the line of the eyes and the mouth is a mean one) be chosen, the resultant portrait will show a minimum indistinctness of eyes, and give what we may fairly call the pictorial average of the group. The average ratio which must serve for fixing the fiducial lines can be obtained from direct measurements on the

negatives. This will not be a formidable task, if, as is usual, the negatives are taken so that the distance between the pupils is the same in all; since in this case it is only necessary to measure the distance from eyes to mouth in each, and take the mean.

This point is one which should be carefully attended to in making composites, for it would seem to be the only normal method of adjustment; all other adjustments giving more or less pronounced variants from the type.

Composites made in this way lose something of the deep-eyed, earnest expression, which is the result of superposing all the eyes of the components on exactly the same points. This loss, however, is a real gain in the truthfulness of the composite portrait, for the deep dark eyes do not represent the average, but rather a summation, and hence exaggeration of earnest expression. The face in fig. 1 is, I believe, a fairly normal composite of the group of forty-nine from which it was made; fig. 4 is from a group selected for facial symmetry, i.e., constancy of the ratio indicated, and is a type of this group with the exaggeration which comes from superposition of the eyes. Questions as to the possible dependence of the result on the order in which the components are taken, and on the time given to each exposure, occur to every one who interests himself in composite photography. In Mr. Galton's earliest paper on the subject, he speaks of six composites made from the same three components taken in their six possible combinations, and says, "It will be observed that four at least of the six composites are closely alike, . . . the last of the three components was always allowed a longer exposure than the second, and the second than the first, but it is found better to allow an equal time to all of them. In a later experiment, composites were made of four differently colored disks, whose images were superposed in four different orders, while the times of the successive exposures were equal. The result was four composite disks of precisely uniform tint.' The inference from this is, of course, that the order of exposure makes no difference when the times of exposure are equal (equal illumination of the image is assumed). The experiments which I have made on this point by taking composite portraits from the same components in different orders (with equal times of exposure) have shown that the order of exposure does affect the result. I have also repeated Galton's other experiment in several modified forms, both with disks of colored paper and with colored glasses (by transmitted light), and obtained results which, especially in the case of the

colored glasses (by far the fairest test), confirm those of Galton.

Experiments of this kind are far more satisfactory than those in which composite portraits are made from the same components taken in different orders for one has to decide in the one case merely on the identity or difference of tint of disks or rectangles placed side by side on the same plate; in the other, of faces with their manifold detail.

Answers to both of these questions as to order and time of exposure would be found in knowledge of the rate at which light acts upon the silver salts of the photographic plate.

If the rate of this action is constant up to the point of a full-timed' plate, then the order in which the negatives are taken can make no difference, provided each successive fractional exposure is of equal length, and the image is in each case equally illuminated. If the velocity with which the chemical action proceeds is not constant, then the order will obviously make a difference in the result, unless the exposures are prolonged or shortened, or the illumination made stronger or weaker, as the velocity decreases or increases.

As far as I am aware, we have no knowledge of the rate of chemical action in this instance, except that which is given by the experiments above referred to, and which points to a constant rate of action within the limits of ordinary photographic exposures. Thus Galton's process appears as a valuable auxiliary in the investigation of an interesting point of the obscure field of photographic chemistry.

The possibility of the 'prepotency' of some individual of the group as a disturbing element was suggested in Science, v. No. 118, and has since been discussed by Mr. Jastrow in vol. vi. No. 134. Since the composite portrait is the result of the action of light on the silver salts, it would seem plain that no one face, however 'individual,' 'powerful,' or characteristic' it may be, can be prepotent in controlling the result. We must conclude that the apparently prepotent face is merely a close approximation to the type or average of the group.

In the hope that more may be induced to do something in composite photography, I would say that excellent results can be obtained with an apparatus which is by no means elaborate or costly. A camera for the purpose can be made of soft wood by any skilful carpenter. It need differ from the usual form only in having a mirror which is hung within so that it can swing down to an angle of 45° for the adjustment, and up against the top for exposures; and an opening in the top, over which a ground-glass plate is fixed. On this ground glass the fiducial lines are drawn

in lead-pencil, and the images focused and adjusted. It must be at the same optical distance from the lens (the light being reflected to it by the mirror) as the ground glass at the back of the camera. A piece of ground glass placed behind the negatives will serve very well in place of a condensing lens for lighting them, and it is not necessary to enclose the gas jet in a lantern.

In order to give accurately timed exposures, I use a pendulum consisting of a wooden rod with sliding weights above and below the point of suspension, and having an arm at right angles to it. At the extremity of this arm is a screen of card or ferrotype plate, which, when the pendulum is swinging, plays up and down in front of the camera tube. Matters are so arranged, that, when the pendulum is at rest, the lower edge of the little screen lies across the horizontal diameter of the tube. After the negative is adjusted, the screen is held down so as to cover the end of the tube, while the slide in front of the sensitive plate is drawn, and then released and allowed to make a double vibration. The time of exposure is that of a single vibration of the pendulum, and this is regulated by adjustment of the sliding weights.

I find, as others have doubtless found, that the best composites are obtained from very 'dense' negatives. Those from which the composites in this number were taken were made for me by Mr. Lovell of Northampton, who succeeded admirably in obtaining strong negatives of very uniform density. JOHN T. STODDARD.

NATIONAL EDUCATION ASSOCIATION. IN point of numbers, the National education association meeting at Topeka, Kan., was among the most important ever held. As far as permanent educational literature is concerned, however, the contributions hardly correspond to the size of the gathering. The real value of such meetings must always be found in the quiet friction of mind with mind, and in the informal talks where men learn the experience of their fellow-teachers and become acquainted with the educational sentiment of distant sections. There is no better place than these to feel the educational pulse, and learn the temper of teachers on mooted points.

Both in the association and the council that preceded, the subject of industrial education was discussed at great length and with the widest divergence of opinion. Dr. S. H. Peabody of Illinois presented the report, which was an admirable paper, clearly and without prejudice outlining the theory of industrial education. To an outsider this whole question seems unnecessarily forced to the front. Only three per cent of our

population are living by the branches of industry in which it is proposed to establish departments of instruction. Still further, one who watches the boy of to-day will hardly find him lacking in practical ability. The great need is rather moral and political training and general culture. Principal Council of the Alabama (colored) normal school at Huntsville gave explicit and convincing testimony to the value of manual training in his school; but the condition of the south, especially that of the colored people, is so abnormal and so different from that in other parts of the country, that a general argument cannot be fairly based on it. The negro is not simply illiterate, he is ignorant, ignorant of thrift, of ways of living, of all that goes to make a prosperous citizen; and industrial education is simply one of many ways to help him. Besides, the educational system at the south is a bare outline. It will stand some filling up. But in the north, and at the east especially, the school system has taken on load after load, until its friends momentarily wait in anxiety lest it reach the breaking-point. The enemies of the public schools are foremost in insisting that its load be increased, doubtless not without sinister

reasons.

Pres. William Preston Johnson of Tulane university, Louisiana, in his paper on education in his own state, spoke of Louisiana as lowest in the scale of literacy, only forty-nine per cent of its population being able to read and write. He pleaded for the national aid proposed by the Blair bill. There was, however, in his paper, nothing to offset the arguments that have been urged against the bill. It is hard for a close student to see how the mere lavish outlay of money is greatly to overcome conditions which money can only indirectly and remotely affect.

In the department of higher education Dr. Mowry of Education read a paper on The college curriculum.' The subject was well thought out, but presented from the ultra-conservative point of view, which is meeting such sharp criticism in many quarters at the present time. The sense of the crowded meeting in which Dr. Mowry's paper was read, was, however, clearly with him. The discussion was sharp.

The subject of alcohol and narcotics occupied large space in the meetings. The presentation was vigorous, though nothing was set forth new to those familiar with the work.

A department of secondary education was formed at the request of the high school and academy men present. It will be restricted exclusively to work between the elementary schools and the colleges.

The department of musical education suffered a

serious loss in the absence of its president, Dr. G. Stanley Hall, who was detained at Ashfield, Mass. The papers read offered no noteworthy addition to the present literature of the subject.

The kindergarten and industrial displays were unusually attractive; the Kansas agricultural college occupying a prominent place, and displaying some excellent work.

Altogether the meetings may be held a success. The place chosen was hardly fortunate, public accommodations were frightfully limited, and the heat at times was appalling. But western hospitality never showed itself in a more enthusiastic and delightful way. Houses and hearts were cordially open, and the torrid weather was cool compared with the welcome extended an all sides.

THE HEALTH OF NEW YORK DURING JUNE.

THE population of New York on the first day of June may be considered as 1,435,290. Of this number, 2,762 died during the month, an excess of three as compared with May. While, however, the total mortality for the two months was so nearly the same, the number of deaths of children under five years in June greatly exceeded that of the preceding month: the deaths in June being 1,375, as compared with 965 in May; or, to represent it in another way, had the conditions in June been the same as in May, 410 children whose deaths are recorded at the health office would now have been alive. The greatest daily mortality from all causes occurred on the 26th. On that day 124 persons died, 43 of them being under one year of age, and 66 under five, or more than onehalf of the total mortality being children of this tender age. The causes of death on this day were as follows: 32 persons died from diarrhoeal diseases, 13 from consumption, 12 from diseases of the brain and nervous system, 8 from diseases of the kidneys, 5 from diphtheria and the same number from cancer, 4 from pneumonia, 3 from croup, and 2 from rheumatism and gout. Consumption still leads the list as a mortality factor; taking the month as a whole, 423 persons having succumbed to that disease, 72 less than in May. Diarrhoeal affections increased more than fourfold, these deaths being 303, as compared with 73 in May. Diphtheria, with 130 deaths, showed a reduction of 35 deaths; while scarlet fever is charged with but 29 deaths, as against 44 in the month preceding.

The meteorology of the month is full of interest. The mean temperature for the year has been as follows: January, 26.79° F.; February, 27.45° F.; March, 37.60° F.; April, 52.87° F.; May, 60.18° F.;

June, 68.03° F. As compared with the preceding sixteen years, June of 1886 was a cool month in but two years, 1879 and 1881, has the mean been so low. The maximum temperature was 84° F.: this was reached on the 10th at 5 P.M., on the 17th at 1 P.M., and on the 29th at 5 P.M. In no year since 1869 has the maximum been so low for the month of June, the lowest being 88° F. in 1881, while it has in thirteen different years since 1869 been in the nineties, and in 1874 was as high as 98° F. The rainfall for the month was 3.35 inches, slightly above the average for sixteen years, which was 3.01 inches: it was less than that of May by 2.05 inches, but greatly in excess of that of June, 1880, which was only 1.32 inches. The number of days on which rain fell was nine.

It is of interest, in connection with the subject of temperature, to compare the maxima as recorded in the cities of New York and Brooklyn. The meteorological observations for the former city are made at Central park at a height of 97 feet above the sea: those for Brooklyn are made at Prospect park, 220 feet above the sea-level. The following table shows the maximum and minimum temperature for each day of the month of June at these two recording-stations, and the mean for the weeks ending June 5, 12, 19, and 26.

June 12.

June 19.

に安さに思に

62 60

71 66

57 63

54

57

57

59

62 65

62 60

62

60

65

64 63

66

63

63

June 5. June 26. N.York B'klyn N.York B'klyn N.Y. B'klyn N.Y. B'klyn 66.5 65.98 1 68.8 68.86 67.3 65.98 68.4 67.19 It will be seen that Brooklyn has, as a rule, a lower temperature than New York. Whether this is due to the difference in elevation of the readingstation, or to some other cause, we do not know. At some future time we hope to be able to give the record of temperature as observed in the hearts of the two cities, which is really the temperature which has a direct bearing upon the public health, rather than that which obtains at such salubrious localities as Central and Prospect parks.

PARIS LETTER.

As the centennial anniversary of the French revolution is to be celebrated here with great display, the government is pushing on with great eagerness all preparations concerning the exhibition of 1889. The plan of the buildings is not yet exactly chosen, but will be soon. It is, however, already decided that a large and very high tower shall be erected in the middle of the exhibition buildings. The Eiffel tower—as it is called, after the name of the man who is to build it will cost a million of dollars. It is to rest on two legs, which meet and coalesce to form a single tower supported by them. The arch thus formed will be wide and high enough to allow a free and easy passage to the whole of Notre Dame, if this cathedral were to come and ramble about the exhibition. The whole tower will be seven times as high as the Arc de triomphe. At present the question is how one shall get up to enjoy the very fine view that will be afforded from the top. An elevator can be used only in the vertical part of the tower in the two legs, one must devise some other plan, on account of the incline. It is believed that in the first, non-vertical part, a funicular railway will be used; in the other an elevator will do very well. But, of course, both systems must be very well combined, and every thing possible must be done to insure the safety of the amateurs who wish to ascend the tower. This is not the easiest part of the task of M. Eiffel. The building is to be begun as soon as the necessary funds have been voted by the senate.

A very interesting meeting was recently held at the Academy of inscriptions. Some days after I sent my last latter, it was rumored that M. Maspéro, the very modest and able director of the Boulaq museum of Cairo, had found some very antiquated and interesting mummies. These were found, as he wrote to the academy, in a cachette of Deïr el Bahari, not at all in their tombs: they had been hidden to prevent violation. The mummies were undone in presence of Nubar-Pacha, Sir Drummond Wolff, and the khedive.

It was then easily ascertained, by means of the inscriptions on the cloths surrounding the mummies, that one of them was the body of Ramses II. This is certainly a very interesting fact; and it is easily believed that to assist at the unveiling of the corpse of a great conqueror, such as Ramses, who died forty centuries ago, causes an emotion of a rare and novel nature. A photograph of the mummy was produced at the meeting of the academy, and created quite a sensation. Although forty centuries have passed over this dead body, the face is in an excellent state of preservation. The