No. XVIII.] APPENDIX. 277 



been exposed to the exhalations of drains, cesspools, &c., or to the equally 

 hurtful products of the lungs and skin of other individuals. Hence these 

 facts may be expressed hypothetically, by assuming that from some cause 

 the diffusive power of the atmosphere is at the present time below the 

 average ; and hence, wherever noxious exhalations exist, there the disease 

 is manifested according to the susceptibility of the unfortunate individuals 

 exposed to their influence. 



The non-diffusive hypothesis meets every case with which I am 

 acquainted in this great metropolis; for, from having carefully studied 

 the official facts communicated by the Registrar- General, together with 

 other observations, I have been surprised how constantly cholera has 

 appeared upon the lines of the great sewers. 



The Fleet ditch, which is almost a river in the magnitude and length 

 of its course, has furnished abundance of cases, and its immediate neigh- 

 bourhood many more, from causes which I shall presently detail. This 

 sewer runs its course along the lowest ground between two hills, Ludgate 

 Hill on the one hand, Fleet Street on the other. When the sun shines 

 upon the hills, the air becomes warmer and specifically lighter, and hence, 

 according to immutable physical laws, a circulation of air laden with the 

 hurtful gases is produced in a direction from the river to these streets, and 

 with a magnitude of current directly proportionate to the imperfection of 

 the trappings of the sewers. This life-destroying blast is perceptible to 

 the olfactory organs of the most indiscriminating person. 



The cholera does not necessarily follow water, because no case has 

 occurred along the New River, which is a pure, pellucid stream, running 

 at a considerable altitude along the hills, and which therefore does not 

 imbibe the drainage in the neighbourhood. At Highbury Yale a foul 

 ditch runs, and there, I am informed, the malady has occurred. From 

 these facts we learn that water without a sewer is harmless. 



The non-diffusive theory, which I submit is competent to account for 

 the fact of cholera, shows that the public have incurred a grave responsi- 

 bility for not having removed effectually the excrernentitious matter from 

 London, as it points out that every death from cholera is a homicide which 

 might by proper management have been prevented. 



The most indifferent person must have observed that noxious vapours 

 do not diffuse with equal rapidity at different times, and a question 

 naturally arises, how far electricity may be supposed to influence that 

 state. When particles of matter are electrified similarly, they repel each 

 other ; when dissimilarly, they are mutually attracted. As far as gases are 

 concerned, I do not know of any experiments which bear upon the matter ; 

 and so far as my own attempts have at present gone, I do not feel at 

 present satisfied with the results. During the prevalence of cholera the 

 electrical state of the atmosphere has been neutral ; and when thunder- 

 storms have occurred, the electrical disturbances have only been manifested 

 for a few hours. This neutral state is probably most favourable for the 

 non-diffusion of gases.* It is probable this non-diffusive state does not 



* Connected with this subject, we must not forget the presence of ozone 

 in the atmosphere. It has the properties of a highly-oxygenated substance, 

 and hence would enter into combination with mephitic bodies. This curious 

 substance is produced whenever electricity is passing through water or aqueous 

 vapour, and is, .perhaps, identical with the peroxide of hydrogen. 



