144 JOHN M. SMAIL. 
It would be difficult to find another subject upon which so 
many diverse opinions have been advanced or systems patented. 
A review of the various systems adopted or tried in the earlier 
years of what might be termed modern sanitation, would indicate 
that very little advance had been made in sewer ventilation, 
beyond that known and practised by the ancients Romans. The 
remains of the colossal works carried out under the rule of various 
Roman Emperors, indicate at that remote period, that they were 
fully alive to the necessity of ventilation for all conduits under- 
ground as well as for the sanitary portions of the buildings, 
Shafts were sunk one hundred and twenty feet apart for ventila- 
tion, and to admit of workmen entering to effect repairs—some of 
these shafts, history informs us, remain to the present day a fitting 
monument to the builders. Coming to modern times, we find 
- that sewer ventilation did not assume a practical form until the 
inception of the Main Drainage Works of London by the Metro- 
politan Board of Works, the system adopted by the engineers 
differed very little from that carried out by the Romans. The 
general principles laid down being that there should be manholes 
(shafts) at certain intervals opening direct into the roadways— 
these shafts, and in some cases lampholes were fitted with iron 
gratings. It will be seen by these measures, that the sewer was 
placed in direct communication with the external air. For a con- 
siderable time this was considered the orthodox method of dealing 
with the question, and for years afterwards was adopted by every 
town in England and elsewhere where sewerage works were 
carried out. 
No other city in the world has expended more money in dealing 
or experimenting with the sewage question than London, and it 
is to England we must look as the cradle of sanitary science. 
Notwithstanding the scientific principles adopted at the incep- 
tion of the primary works, complaints arose from residents within 
the immediate vicinity of the open ventilators, and the minds of 
the various authorities were exercised as to the best means to 
overcome the difficulty. The sewer was voted as the root of the 
