Heatconditionmean+mean−mean+mean−meanYears1869187618811886–871891–921870–751877–801882–861881–911892
Heatconditionmean+mean−mean+mean−meanYears1869187618811886–871891–921870–751877–801882–861881–911892
Having these solar data, the next thing to do was to study the Indian rainfall during the southwest monsoon for the years 1877–1886, the object being to endeavor to ascertain if the + and − temperature pulses in the sun were echoed by + and − pulses of rainfall. The Indian rainfall was taken first because in the tropics the phenomenaare known to be the simplest. It was found that in many parts of India the + and − conditions of solar temperature were accompanied by + and − pulses, producing pressure changes and heavy rains in the Indian Ocean and the surrounding land. These occurred generally in the first year following the mean condition, that is, in 1877–78 and 1882–83.
The rainfalls at Mauritius, Cape Town, and Batavia were next collated to see if the pulses felt in India were traceable in other regions surrounding the Indian Ocean to the south and east. This was found to be the case.
A wider inquiry was followed, we are told, with equal success, so that we are justified in hoping that the question of the dependence of terrestrial upon solar weather has made a step in advance.
But just as the general public and practical men took little heed of the connection between sun spots and magnetism until experience taught them that telegraphic messages often could not “get through” when there were many sun spots, so the same public will not consider the connection in regard to meteorology unless the forecasting of droughts and famines be possible.
The recent work suggests that, if the recent advances in solar physics be considered, the inquiries regarding rainfall may be placed on a firmer basis than they could possibly have had in 1872, and that such forecastings may become possible.
What was looked for in 1872 was a change in the quantity of rain at maximum sun spots only, the idea being that there might be an effective change of solar temperature, either in excess or defect, at such times and that there would be a gradual and continuous variation from maximum to maximum.
We see that the rainfalls referred to above justify the conclusions derived from the recent work that two effects ought to be expected in a sun-spot cycle instead of one.There was excess of rainfall, not only near the sun-spot maximum, but near the minimum.
If the authors of this communication to which I refer are right, then droughts and famines occur in India because the rain pulses, which are associated with the solar-heat pulses, are of short duration. When they cease the quantity of rain which falls in the Indian area is not sufficient, without water storage, for the purposes of agriculture; they are followed, therefore, by droughts, and at times subsequently by famines. They divide the period 1877—89 as under:
Rain from − pulse{ 1877.{ 1878.{ 1879 (part).No rain pulse{ 1879 (part).{ 1880 (central year).{ 1881 (part).Rain from + pulse{ 1881 (part).{ 1882.{ 1883.{ 1884 (part).No rain pulse{ 1884 (part).{ 1885 }(central year).{ 1886 }{ 1887 (part).Rain from − pulse{ 1887 (part).{ 1888.{ 1889.
Rain from − pulse{ 1877.{ 1878.{ 1879 (part).No rain pulse{ 1879 (part).{ 1880 (central year).{ 1881 (part).Rain from + pulse{ 1881 (part).{ 1882.{ 1883.{ 1884 (part).No rain pulse{ 1884 (part).{ 1885 }(central year).{ 1886 }{ 1887 (part).Rain from − pulse{ 1887 (part).{ 1888.{ 1889.
Their statement is based on the fact that all the famines which have devastated India for the last seventy years have occurred at intervals of eleven years, or thereabouts, working backward and forward from the central years 1880 and 1885–86 in the above table, the middle years, that is, between the pulses.
Mr. Willcocks, in a paper read at the Meteorological Congress at Chicago, remarked that “famines in India are generally years of low flood in Egypt.”
It is now pointed out that the highest Niles follow the years of the + and − pulses, as does the highest rainfall in the Indian area.
Even if these results, which were communicated to the Royal Society of London five weeks before the end of the century, be confirmed, it may be pointed out that Sir William Herschel’s suggestion of 1801 will have required a whole century for its fulfilment, so slowly do those branches of science move which have not already led to some practical development.
Norman Lockyer.