Umbrellas, necessity of, [11]
Vaccination, cause of sore arms after, [140], [141];
discovery of, [132];
how, prevents smallpox, [135];
necessity of repeating, [137];
pretended vaccination, [138];
when successful, [138]
Ventilation, in homes, [46], [159];
in public buildings, [48], [161];
in workshops, [48]
Veins, [171]
Villi, [171]
Vitreous humor, [178]
Voluntary action, [181]
Water, avoid polluting, [85–88], [115];
effect of sewage on, [85], [115];
how germs get into, [85–88];
polluted, in milk, [27];
safe sources of, [88]
Wells, how polluted, [86], [87];
relation of toilets to, [86], [87]