108 



villages were therefore visited and among 392 persons examined 

 (including the above 123), 10 cases were found. All these places are 

 within a short distance of the Luangwa River and may be said to be 

 within the same fly belt. Glossina morsitans was scarce. The disease 

 is beheved to be recent in this locality. 



Le Prince (J. A. A.) Malaria Control-Drainage as an Antimalarial 

 Measure. — Public Health Reports, Washington, D.G., xxx, no. 8, 

 19th February 1915, pp. 536-545, 13 figs. 



Under the following heads the author discusses the special type of 

 drainage required for mosquito control and eradication which, while 

 ensuring drainage of the land, will not provide breeding places :— 

 Training natural streams and water courses ; open ditches and intsr- 

 cepting ditches ; the installation of permanent lining in ditches ; 

 subsurface drains ; filling ; and proper maintenance. A stream 

 should have steep banks directly above and below the flow line, uniform 

 grade and width, a straight course, and be free from grass, sticks, 

 stones, and other obstructions to the current. Directions are given 

 for attaining these results, which chiefly involve questions of proper 

 regrading. There should be as few ditches as possible and they should 

 have clean-cut, sloping edges, narrow bottoms and straight courses. 

 Instead of repeatedly regrading, cleaning and oiling ditches or portions 

 of them, it is often cheaper to line them with concrete. Stone with 

 cement, mortar, lumber, or concrete may be used. For small ditches, 

 the hning need only come up to 3 inches above the normal water Hue. 

 To prevent side scour above the lining, especially at curves and bends, 

 the outer wall liuing may be raised or the ditch may be widened or 

 key walls installed. The latter will also prevent side scour and imder 

 scour of straight ditches of heavy grades. Weep or seepage holes 

 are necessary above the key wall and should slope towards the centre 

 or bottom of the ditch. They drain the water behind the lining and 

 should be made in the sides of the lining before the concrete has set. 

 Linings should be U-shaped with sloping sides. With the aid of 

 diagrams, the different principles involved are explained where subsoil 

 drainage by means of drain tiles is employed for the purpose of lowering 

 the water table and for that of intercepting seepage. The subsurface 

 drain has the following advantages over open ditches : — It is self- 

 cleaning, it maintains itself, permits of rapid inspection, needs very 

 little attention, requires no oiling and does not permit of water being 

 accessible to mosquitos. Cinders are very good for filling ground. 

 The destruction of algae by copper sulphate is mentioned, and the 

 quahfications of the inspector required and his work are described. 



Le Prince (J. A. A.). Control of Malaria. Oiling as an Antimosquito 

 Measure. — Public Health Rejjorts, Washington, B.C., xxx, no. ^, 

 26th February 1915, pp. 599-608. 



In treating mosquito-infested waters with oil, it is not practicable 

 to state how much oil should be used per unit of area. The density 

 and spreading qualities of various shipments of commercial oils, even 

 of oil from the top and bottom of the same barrel, may vary so much 

 as to upset all calculations. Just sufiicient oil should be used to form 



