34 DR. R. ANGUS SMITH ON THE 



stands high ; but as there are several species from several 

 situations, the numbers vary considerably. 



In a list where the highest breaking weight is 1 1158 lb. 

 in the case of white or pale iron bark, the blue gum of 

 New S. Wales is 7364 to 6860, of Queensland 56'63, 4074, 

 3416 ; and as a means of comparison may be given Russian 

 Larch 2142, White Cedar, Queensland, 2105; the blue 

 gum, therefore takes a high position. 



That drying is an important element in the removal of 

 the causes of malaria cannot be doubted in most cases ; 

 but it is by no means apparent iu all. It cannot be 

 doubted that Garibaldi^s plan of having another passage for 

 the Tiber south of Rome would be of great advantage, but 

 especially to the city itself, which is so frequently inun- 

 dated, and which must therefore be on a foundation ex- 

 ceptionally wet. The mud brought down is proverbially 

 great ; but, so far as I could judge^ it was not so fine as that 

 of the Nile, which, however, I have seen only in bottles. 

 The Egyptian mud causes no fevers, perhaps because it is 

 more rapidly dried up. The mud of the Tiber is deposited 

 on a very deep soil ; but the same occurs on the Nile. The 

 depth of mud, however, may have an important bearing in 

 a less-burning sun ; but I cannot see how it affects the 

 question of malaria. 



The mud of the Tiber seems always to have been re- 

 markable ; and one wonders why it should be able to go on 

 so long unchanged. But on going up the river the difficulty 

 ceases ; there we find mud hills, many of them conical, all 

 with steep sides, and nearly all without any vegetation except 

 below in some cases. There is in fact from the water an 

 enormous deposit raised to a great depth, and enough to 

 keep the Tiber as muddy as ever for ages. It seemed to me 

 that all this fine earth would be very valuable in much of our 

 country, where we are glad of a few inches over chalk, or 



