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Popular Science Monthly/Volume 34/November 1888/Sun-Power and Growth


WE know that our planet retains the position which it occupies in the solar system through the force of gravitation; we know, furthermore, that all organic life on our earth depends upon the warmth and the light which it receives from the sun; but of the intimate relation which exists between organic life and the changes taking place on the sun we are in comparative ignorance, notwithstanding investigation has brought to light a number of important facts.

That the growth of plants in our zone stands in intimate relation to a rise in the temperature of the earth is well known; but the fact that a force varying in intensity and influencing the growth of the human organism proceeds from the sun is a discovery as novel as it is interesting. Some phenomena, possibly referable to a property of this kind, were observed during an experimental investigation of the diet furnished to the inmates of the Royal Deaf-Mute Asylum at Copenhagen.

When, some years ago, a change of diet was proposed for the inmates of this institution, the director, the Rev. R. Malling-Hansen, thought it desirable to obtain a clear idea of and some definite data concerning the thriving of the children under the system then practiced, by which the results and the value of the new system of nourishment proposed could later on be accurately determined. The conscientiousness of the superintendent and pastor of the asylum would not permit the permanent substitution of a new system of diet without first possessing some facts by which its advantages or disadvantages would be plainly pointed out.

For this purpose the children were daily weighed and measured in groups, in which manner the total weight of the pupils was quickly and accurately ascertained. The technical details as well as full statistics on the subject will be found in Rev. Malling-Hansen's work, "Periodicity in the Weight of Children and in the Heat of the Sun" (Copenhagen, V. Trydes). These weighings present some very interesting facts.

(Until then it had been supposed that the growth of a number of children (of different ages) averaged the same throughout the year, and that the increase in weight as well as in height of a greater number of children might be registered by a straight line slanting upward. The annotations of the weighings and measurements of the Royal Deaf-Mute Asylum at Copenhagen proved, however, that the universally accepted biological theorem is wrong, for the weight-lines of about seventy children had no even gradation but showed great changes during the year. During each of the three years the greatest increase in weight took place in the fall until the beginning of winter, then till the end of April the increase grew less, and after this time a loss in weight was noticed. At times the increase in weight of the children would cease suddenly for a few days, and occasionally during the time when an increase was expected a general decrease occurred. Based upon his measurements and annotations, Malling-Hansen framed the following rule: The weight of a boy ranging from the age of nine to fifteen undergoes three periods annually—a maximum, a medium, and a minimum period. The maximum period lasts four and a half months, commencing in August and ending the middle of December; the medium stage has the same duration, from the middle of December to the end of April. The minimum period appears during the remaining three months, from the end of April to the end of July. The increase in weight during the maximum period is three times that of the medium period, and almost all the gain of the medium period is again lost during the minimum period. From the working of this law it follows that in changing the diet at academies, schools, and asylums, the season should be considered. A good diet would give less satisfactory results if observed from April to June, than a poorer diet if noted from August until December.

In the same manner as the increase in weight, the increase of growth fluctuates, and can likewise be divided into three periods. These periods commence and close about a fortnight before the periods of weight, but in such a manner that the minimum period of growth occurs at the time when the weight remains stationary, and may at times even be coincident with important loss in weight. Growth takes place, one might say, at the expense of the increase of weight. Accurate observation showed that the general growth of the trees in the garden of the institution corresponded essentially with the growth of the children. The maximum period of growth upward is followed by that of increase in circumference. The growth of the human body and the growth of the trees are consequently influenced in the same manner by some disposing cause. But what is this cause?

As the fluctuations referred to above coincided strikingly with the fluctuations of atmospheric warmth, Malling-Hansen believed that they could be attributed to local meteorological conditions; and it was really shown that with a rise of temperature the weight increased, and vice versa. It was, however, ascertained that during the minimum period a rapid rise of temperature but slightly affected the increase in weight, and in the same way the decrease in temperature during the maximum period influenced the weight but little.

Furthermore, it seemed remarkable that the children should lose in weight instead of gaining, with the progressive rise in temperature in spring and in early summer, and that in fall the opposite relation should obtain. If heat alone were the active medium, the warmth indoors in winter would exert some influence; this was, however, not the case. Many other observations indicated that local changes of temperature were not the looked-for cause, as the fluctuations in weight of the inmates of the Royal Asylum corresponded to those of the deaf-mute children, notwithstanding the great difference in the location and surroundings of these two institutions. The force, moreover, seemed not to be influenced by the seasons, but to continue invariable during frost and heat, during sunshine and rain; its action on the whole was not affected by the warmth of indoors or by the cold without.

The fluctuations of the increase in weight were more regular than those of temperature; these fluctuations, with their great variations and their periodicity, seemed to show that organic growth, of both human beings and animals, is affected by some to us as yet unknown cause. This influence is partly mirrored in the local fluctuations of temperature, and these again, of course, are in connection with the sun.

If the inference should prove correct that increase and decrease in weight vary with the solar radiation, the thermometric registration of places on the Continent, not exposed to sea-winds, would coincide more accurately with the results of the weighings than the local climatic condition of Copenhagen would render possible.

Mr Malling-Hansen undertook the task of tracing in curves the fluctuations in temperature of different meteorological stations recorded in the Danish Institute of Meteorology. The stations, which are at the following places, permit a broad view, as they are at great distances from one another: Copenhagen, Vienna, San Fernando, Lucknow, Tragpoor (India), Paramaribo (Guiana), Cordova (Argentine Republic), Port Dover (Canada), and Vioi (on the Congo).

The more these curves were compared with one another, the more did they show a remarkable analogy between the fluctuations of temperature over the whole globe, and the fluctuations in the weight of the children at Copenhagen. And, furthermore, the curious fact was discovered that the fluctuations in temperature in India, as well as in Copenhagen and in North and South America, varied in a similar manner, and were analogous to the fluctuations shown in the weight-increase of the children in accordance with the variations of temperature experienced at the different places. All these fluctuations in the weight of the children picture the result of an influence emanating from the sun.

All the growth on the globe, from the most minute to the largest being, from the simplest to the most perfect organism, with, all its variations and fluctuations, stands in close relation to the sum-total of heat of the earth's atmosphere.

As, however, the warmth of the sun is influenced differently at different places by clouds, by wind, and by dampness, it never reaches the organisms in its original condition. Notwithstanding this, however, the fluctuations of weight-increase progress in harmony. Whatever it is that thus influences growth comes to us with the speed of the sun's rays; it varies from day to day, its intensity is the same at the same time throughout the globe, and it is not subject to local causes, to changes by wind and by weather.

Malling-Hansen calls this force "energy of growth"; he supposes that it reaches the earth with the speed of the heat-rays; separates from these, undergoes manifold changes, and, spreading over the whole earth, is the cause of the uniform fluctuations in the growth of all organic life. Upon future investigations falls the burden of proof of this assumption.

This influence of the sun-power may serve as an important factor in testing systems of nourishment, in the arrangement of diet-cures, and in studying the action of mineral waters. For instance, what weight can be attached to an opinion formed on the medicinal value of a mineral spring, if the test be made at a time when the energy of growth is on the decrease, and is thus perhaps assisting in the action of the spring, which at some other period might prove itself only half as efficient?

Good nourishment, a limited amount of mental effort, and as far as possible healthful surroundings during the maximum period of growth of girth, may tend to re-establish the right proportion of stature in children who have grown too rapidly.

There is no known reason to doubt that adults gain and lose in the same periods. If persons who are desirous of growing less stout leave the watering-places at the end of August or earlier, they do so at the time of weight-increase, and a careless diet will hence, in shorter time than it would under similar circumstances in winter, cause them to grow stouter again.

With regard to the school vacations, these should be given from the end of June to the beginning of September, during the two maximum periods of growth; the bodily strength which has been gained will aid the mental work.—Translated for the Popular Science Monthly from Daheim.


Prof. Gairdner has called attention, in the British Medical Association, to the need of medical students receiving more adequate instruction in physics. The subordination of living bodies and physiological processes to all the most elementary laws of matter; the correlation of all the physical forces; and the medical methods involving applications of pure physics, combine to make this matter an extremely important one. The physical laboratory will probably in a very few years become an essential aid in the education of the physician.