136 
The ratios of the velocities at Eccles to those at South- 
port are therefore greatest with south-west and north-east 
winds, and least with north-west and south-east winds. 
The great excess of velocity of north-west winds at South- 
port is very remai'kable. 
The results of the above comparison bring out very pro- 
minently one of the causes of the great salubrity of South - 
port as compared with the neighbourhood of Manchester, 
namely, the much greater mean velocity of the wind, in 
consequence of which the products of decomposition, and 
and offensive matters generally which are injurious to 
health, are much more rapidly removed at Southport than 
at Manchester. 
MICROSCOPICAL AND NATURAL HISTORY SECTION. 
February 5th, 1872. 
Joseph Baxendell, F.R.A.S., President of the Section, in 
the Chair. 
Mr. Joseph Sidebotiiam, F.R.A.S., called the attention of 
members to the mass of correspondence in the papers on the 
origin and spread of Typhoid fever, in which it seems to be 
considered as proved that the fever is produced by what are 
termed sewer gases, and the germ theory is entirely ignored, 
when in all probability it is the true one. The various 
gases found in sewers are well known, and if produced 
artificially, as they are in various chemical processes either 
alone or mixed, are comparatively harmless, even in a more 
concentrated form than they are ever met with in sewers, 
at any rate they never produce typhoid fever. If the germ 
theory be correct the real agents in the spread of this and 
other similar diseases are germs or particles, many of them 
sufficiently large to be detected by the miscroscope ; these 
are met with in sewers, but probably not generated there, and 
