Rainfall Curve Research Articles

Prophylaxis of malaria in the Sudan. With special reference to the use of plasmoquine

Malaria is most prevalent in the Gezira between October and January, following a well-defined seasonal periodicity. All three types of infection occur, malignant tertian being most prevalent. The incidence of the disease follows the rainfall curve at an interval of approximately two months. The only infecting mosquito worth considering is Anopheles gambiæ which is most prolific from September till February and possibly æstivates during the summer months. Naturally infected mosquitoes never exceed 2 per cent. The human carrier of the disease is chiefly the child who is most heavily infected with gametocytes between October and January. Experiments have been carried out to test the efficacy of plasmoquine in causal and gametocyte prophylaxis. Small daily doses of the drug for causal prophylaxis are not recommended as they tend merely to conceal infection. The results of experiments in gametocyte prophylaxis tend to show that a biweekly dose of 0·02 gramme plasmoquine simplex to children might be of considerable value in antimalarial work. Conclusions drawn from the short period under review are suggested with diffidence.

Variations in the Level of Lake George, Australia

ON May 18, 1876, a letter appeared in NATURE from Canon R. Abbay on the subject of the changes in level of Lake George, in the south-east of New South Wales, which in the past hundred years has varied from a small swamp to a depth of 25 feet or more. We have now received from Canon Abbay a letter and a diagram showing the variations of level in the lake from 1817 to 1918. The latter, which is reproduced in Fig. i, was drawn from information compiled by the late Mr. H. C. Russell, Government Astronomer of New South Wales, up to 1904, and since that date by the Commonwealth Meteorological Bureau. It also shows the “residual rainfall curves” for Goulburn, the nearest station, and for Sydney, 150 miles distant. A residual rainfall curve is obtained by finding the difference of rainfall for each year from the average for the whole period and adding up the differences for successive years, so that the figure plotted for any year represents the total excess or deficit of rainfall from the beginning of observations until that year. The curves show, as Canon Abbay points out, that while rainfall is evidently an important factor in the level of the lake, there must also be other influences at work.

Interprettion of Meteorological Records

IN the interesting discussion of the records of Lander and Smith's instruments at Canterbury (NATURE, March 15) both Dr. Aitken (pp. 485, 534) and Mr. Omond (p. 512) appear to have overlooked the fact that no rain fell, but only snow to the depth of more than 1 inch. This snow was mixed with a little hail at the commencement of the storm, but no rain fell as assumed by both your correspondents. The records state that the 0. 26 inch of rainfall consisted of snow melted as it fell. The first sign of the storm was distant thunder and a darkening of the sky in the north-west. The glycerin barometer commenced its usual sharp rise before the first hail arrived and the storm was directly overhead. It is a curious fact that the rain or snow with a thunderstorm occurs with the sharp barometric rise, and not with the fall as one might expect. I think the great fall in temperature was due to the snow, and not as described by your correspondents. The rainfall curve did not begin first as suggested by Dr. Aitken, but the barometer as explained above. It is another curious fact that, although my house is the highest here, and has my anemometer on top of 30 feet of iron tubing above roof, and wireless telegraphy aerial 80 feet above street (with which I was busy at time of storm), yet no damage was done; but within mo yards much lower houses had chimneys and walls thrown down and roofs split, &c., and people were seriously injured. Many houses, windmills, and a church in the district were set on fire.

Cyclical rainfalls at Lisbon

The more strongly marked and decisive character of the curves of lunar monthly rainfall, in Philadelphia than in Great Britain, (ante v. x., pp. 523-34,) rendered me desirous of obtaining observations from some European station in lower latitude. The intimation of that desire to the Director of the " Observatorio do Infante Dom Luiz," at Lisbon, was promptly followed by the transmission of a copy of observations extending over a period of sixteen years, which is herewith presented. I also submit some of the tabulated results of such discussion of the observa-