The subject has lately been investigated by Dr. H. H. Clayton, of Argentina, formerly of Blue Hill, Mass. In such an investigation a natural procedure would be to make two superposed curves, one to show the change of solar radiation day after day, and the other the change of temperature. The trouble with this method is that there are so many influences that operate on the weather, apparently haphazard, that their combined effect often masks the influence under investigation. Accordingly, Dr. Clayton employed the mathematical method of correlation, which has come into general use in biological researches. In this method two functions, like the diameter and circumference of a circle, that are related so intimately that the increase of the one depends only on the increase of the other, are said to have a correlation coefficient +1. Two functions, like the heights of two ends of a balance, which are so connected that increase of one depends only on decrease of the other, are said to have a correlation coefficient -1. Between these perfect degrees of positive and negative correlation lie all degrees of dependence, and a coefficient of correlation, zero, indicates that the variables are unrelated. As in other investigations, it is valuable to determine the probable error of each coefficient of correlation, and one considers a correlation standing alone as demonstrated when its coefficient is numerically three or four times its probable error. A group of correlations may, however, so obviously support each other as to lend certainty to the correlation of individuals of the combination, though these individual members would otherwise be doubtful in view of probable error.

Dr. Clayton determined for about fifty stations, well distributed over the globe, correlation coefficients connecting temperatures with solar-constant values determined at Mount Wilson in 1913 and 1914. As he thought it likely that the terrestrial influence of solar changes would be deferred, he computed the correlations not only for identical days, but for the 1st, 2d, 3d, 4th, and 5th days thereafter. Here are examples of the largest correlation coefficients obtained.

From this we see that at Pilar, Argentina, increase of temperature followed increase of solar radiation, and the maximum effect occurred after one or two days, while at San Diego, California, decrease of temperature followed increase of solar radiation, and the maximum effect occurred after three or four days. The coefficients of correlation at maximum are fully seven times the probable error numerically, so that the connection is well assured. For other stations different values, some positive, others negative, were obtained, ranging down to zero.

When marked on the map the stations of positive and negative correlations were found to arrange themselves very definitely in zones. Speaking roughly, in the zone within the tropics, but broadening over land areas and narrowing over the oceans, the correlation is positive, and so also in the arctic and antarctic zones, and extending down the east coast of North America. In the remainder of the world, comprising the great temperate zones, the correlation is negative.

A similar investigation, but less extensive, was made by Clayton on the relation of atmospheric pressure to solar radiation. Similar zones seemed to be indicated, but where temperatures rose after increases of solar radiation, pressures fell, and vice versa.

For several of the stations, Clayton's investigation indicates the actual numerical changes in temperature which follow a change of solar radiation. From the average of all the decided changes of solar radiation, I find from his curves that for 1 per cent. solar change there was 5.2° C. average change in temperature at Pilar, 1.5° C. at Manila, and 6.3° C. negative change at Winnipeg. Other stations would appear to give equally surprisingly large results. Clayton's figures, however, relate to maximum daily temperatures. It may be reasonably supposed that the changes of mean temperature corresponding to 1 per cent. increase of solar radiation would be half as great, or +2.6°, +0.75° and -3.15° C., respectively, at the three stations. We had been led to expect almost surely not more than 0.7°, and probably not more than 0.2° C.

Five thoughts are suggested by this remarkable result. First, that the figures ought to be confirmed by tests extending over other years and other stations. Second, that if confirmed. they will indicate that secondary processes are set going in the atmosphere by small changes of solar radiation, which, by altering the atmospheric blanketing effect, magnify in some stations, and reverse in others the natural direct effects of the solar fluctuations. Third, that if such large changes of temperature

are thus caused, investigation may be apt to reveal important effects of solar fluctuations on the winds, cloudiness and precipitation. Fourth, that since the outstanding unexplained departures from mean daily temperatures, as illustrated above for Leavenworth, Paris and Sydney, are seldom of much greater magnitude than the changes which are found by Clayton to be produced by changes in the sun, and as the maximum effects of solar changes follow from one to five days after the cause, depending on the latitude of the station, it may be possible that a very large proportion of weather changes will become predictable for some time in advance, if daily measurements of the solar emission shall be secured. Fifth, that since daily solarconstant measurements of sufficient accuracy can only be had by establishing several new observing stations in the most cloudless regions of the earth, at an initial expense of from $5,000 to $10,000 each, and continued expense of from $5,000 to $10,000 per year each, the occupation of this promising field in forecasting is likely to be deferred until after the war is over. At present the Smithsonian Institution is alone making the required measurements, at Mount Wilson, California, and Hump Mountain, North Carolina. Weather conditions are not sufficiently favorable at either station to warrant the expectation that on half the days in the year the solar radiation will be properly measured. A projected station in South America has been deferred on account of war conditions, but may soon be occupied. A bequest of half a million dollars to the Smithsonian Institution would enable it to handle adequately this apparently exceedingly important problem.

EVIDENCES OF FULL MATURITY AND EARLY

DECLINE

By J. MADISON TAYLOR, M.D.

PROFESSOR OF APPLIED THERAPEUTICS, MEDICAL DEPARTMENT, TEMPLE

WE

UNIVERSITY, PHILADELPHIA, PA.

E are blessed in America with a between season known as Indian Summer. As the days of autumn grow cooler to colder, somewhere toward the winter comes a genial glow in the air, a seductive restfulness, a luxurious period of weeks in which to bask gratefully in whatsoever surroundings one may be. This contentful interlude is said to be devised for the purpose of encouraging the primitive redman to do his undone chores, to catch up on his neglected provisioning against the pitiless winter. Just such a tranquil span may be reckoned upon when the sun turns and passes the meridian and looks into the face of man as he fronts the setting.

Not all the pageantry of early aging or over-maturity are inflictions to be endured. A peace oftentimes supervenes; a shedding of earlier anxieties; a settling down to an even progress. These are halcyon days in which the heretofore tempesttossed one may look about, stretch his limbs and give interested attention to what goes on about him.

For most persons the hurly-burly is by then pretty well over; a position of advantage has been reached, the fires of life burn not so brightly, 'tis true, but more evenly. The machinery has become a little worn, weaker in spots, but all bearing surfaces have been abraded to meet each other in a smoother adjustment. There is less friction and far less racking.

When that blessed time has come, one's children are presumably able to look out for themselves; some have left the nest; at least anxieties on their account are subsiding or less urgent. Life's struggles are pretty well settled and progress is accruing.

The body cells are then less irritable; nerve centers are more stable; there is less tension in all voluntary muscles; a general evenness in action has set in. Whatever be our position in the procession of life we know pretty well we must now be content with it, accept such modifications and betterments as we are able to bring about by making the most of what we

have got, what we did with our foundations. Uncertainties are, or should be, nearing their end. From this time on our bodies as well as our careers can only be conserved; not radically changed for better or for worse.

Whatever destiny remains in our hands, to shape it is the part of wisdom to meet that destiny with a serene brow, with thankfulness for what we have enjoyed and are able to retain, to accept the position in life which we have won, to cross off our losses and forget them. It is a time to take account of stock and make up the report upon our trusteeship of that splendid heritage, our body and our mind. Satisfactions will

be the greater if we have given reasonable care to the increments of our talents. Some part of a mature philosophy should then have been achieved, due to so much of mental serenity and discharge of duty as we have been able to command. Then we can pass on to other stages of our biologic evolution; of our journey to the grave.

To those who view their past as a mere category of mental achievements the account may not seem large. Compared with those who merely aimed to survive, to "get along," ours is certainly more varied, more vividly absorbing, more worthy of review or exhibition. We should never undervalue our body, however; it is of paramount subservience to or rather correlated with the mind.

Unless we have kept our material parts in good working order to enfold and maintain our soul or spirit, we have failed to "acquire merit" or to sustain the makings of a healthy selfesteem. Few indeed should fail here; no good reason exists for any one to so fail.

The phenomena of overful maturity and early aging deserve to be known, philosophically accepted and serenely assessed. From early maturity to late old age the characteristic retrograde changes are those of wearing out of structures. This wearing out takes place throughout the whole range of actively changing parts, in those which are constantly at work, and is especially seen in those which work incessantly to keep the body going. The constant wear and tear is shown most in the heart, the blood vessels, kidneys; and back of these come the great regulators of life, the ductless glands.

Back of these also lie those fairly stable structures the brain, and nerve cells. It is being demonstrated by the life insurance experts that breaking down (degenerative) diseases are markedly on the increase among all sorts and conditions of men, in all lands and under all circumstances civilized or savage.