662 SCIENCE PROGRESS 



the depth below the channel bed being not less than ioo ft. The tunnels could be 

 worked, ventilated, and pumped by electricity from a power station in Kent ten 

 miles inland. As to its defence, the Commandant of Dover Castle would control a 

 water lock formed by a dip in the rail level whereby, in case of emergency, the 

 tunnel could be filled with water from floor to roof for a length of a mile, while the 

 entrance would be dominated by the guns of the Dover forts. As Mr. Fell states, 

 the tunnel would be an outward symbol of the permanent friendship between 

 the two peoples, and it is to be hoped that the present decision will not be 

 final. 



The Lancet (January 26, 1918) contains an interesting article on the " Cause 

 and Prevention of Myopia" by Dr. F. W. Edridge Green. It is generally agreed 

 that myopia is an acquired defect resulting from the elongation of the eyeball, but 

 its causation has not yet been determined ; the evidence for the assumption that 

 near work produces near sight being unsatisfactory. Dr. Edridge Green claims 

 that the primary and essential cause is an obstruction of the outflow of the lymph 

 which should empty itself from the lymph space between the retina and choroid 

 into that of the optic nerve. The accumulation of fluid increases the intra-ocular 

 tension and, distending the sclerotic (whose posterior part is weak), causes the 

 eyeball to become elongated. The obstruction may be produced by severe 

 muscular effort, e.g. by lifting heavy weights, when a feeling of tension is always 

 felt in the eyes, which appear, in extreme cases, to be starting from the head. 

 This is more especially the cause of progressive myopia among warehouse boys, 

 porters, and others whose work involves excessive effort, while with those engaged 

 in sedentary occupations the form of exercise taken may be responsible, e.g. 

 wrestling, rowing, digging, and, also, coughing. Thus when signs of commencing 

 myopia appear anything likely to increase the intra-ocular tension should be 

 avoided while, on the contrary, young hypermetropes should take as much 

 exercise as possible. There is no need to avoid reading. No comments on the 

 theory have yet appeared in print. 



The report of the Medical Research Committee on the causation and pre- 

 vention of T.N.T. poisoning is a most interesting document. An immediate 

 result of the absorption of T.N.T. into the system, whether through the skin or 

 otherwise, is a chemical change in the haemoglobin of the red blood corpuscles 

 which shows itself in a pallor or duskiness of the skin with blueness of the lips. 

 This cyanosis does not by itself produce fatal results, and if fresh entry of the 

 poison is prevented the body rapidly recovers. But if the effects are permitted to 

 accumulate two incurable and rapidly fatal diseases may occur, namely, "toxic 

 jaundice" as a result of the destruction of liver substance or, more rarely, "aplastic 

 anaemia " due to the blood-forming organs failing in their function so that a 

 progressive loss of blood takes place. These diseases, however, do not always 

 result from even severe cyanosis ; while on the other hand there seems to be 

 evidence that they have developed without that danger signal first appearing. 

 Different persons have vastly different susceptibilities ; very many are quite 

 immune. Thus one of the main causes of the decreased incidence of disease in 

 1917 as compared with 1916 is that workers whose power of resistance is small 

 have taken up other work. The investigation, which was carried out by Dr. B. 

 Moore, F.R.S., also showed that the main source of absorption was through the 

 skin and not through the respiratory organs. Not only is the T.N.T. which is 

 breathed in as dirt in the air much less harmful than that rubbed in the hands 

 and forearms, but also the amount absorbed per shift is small and easily ejected 

 from the system. Elaborate methods of ventilation are not so necessary as skin 



