222 JOURNAL OF THE PLYMOUTH INSTITUTION. 
2. General Statement of the Case. — Indications of deficient ven- 
tilation; synopsis of its effects. Temperature no indication of 
purity of atmosphere. Causes of impurity of air in dwellings; 
results of respiration and combustion ; products of decay. Measure 
of aerial impurity. 
3. Ordinary Remedies. — Their advantages and drawbacks. 
4. Constitution of the Atmosphere. — Constant and adventitious 
ingredients. Ozone. 
5. Scale of Atmospheric Impurities. — When air ceases to be re- 
spirable. Proportions of carbonic acid in the air of various buildings. 
6. Rate of Production of Atmospheric Impurities. — (a) By re- 
spiration and perspiration, (b) By combustion. 
7. Cycle of Aerial Movements in an Apartment. — Causes and 
courses of currents. Height of rooms less desirable than area. 
Effect of wind on contained air. Causes of failure in popular con- 
trivances for facilitating escape of smoke. Supply of fresh air 
more important than removal of that which is foul. Propagation 
of germs of disease. 
8. Rate of Admission of Air. — (a) For respiration, (b) For 
combustion (illumination), (c) Ditto (warming). 
9. Temperature of Air-supply. — (a) For ordinary apartments. 
(b) For nurseries and sick-chambers. Objectionable methods of 
heating air. 
10. Density of Air-supply. — Of no importance. Plenum and 
vacuum ventilation. 
11. Principal Contrivances for Aiding Ventilation : their Merits 
and Defects. — (a) Cooke's wire-gauze air-openings, (b) Tobin's 
system, (c) Wind-sail and "mulguf." (d) Intersolar air-supply, 
(e) Chimney- cowls. (/) Arnott's chimney-valves. (g) Eickets' 
ventilating globe gas-lights, (h) Watson's ventilators, (i) Inter- 
solar air-drains, (h) Wheeler's system. (I) Edwards' "vomito- 
rium." (m) Hot-air "registers." (n) The author's system. 
