The armies certainly did not escape fever and cholera in their most terrible forms. The French, the British, and the Sardinians alike suffered, both in the field and in hospital, at the commencement. The British alone, however, by means of sanitary works and regulations, reduced cholera attacks to a _minimum_, and almost abolished fever. A few simple alterations to the sewers from the great hospitals on the Bosphorus and other places; ventilation--in many instances by simply breaking the top squares of windows; regular scavenging without and cleansing within the works of the hospitals, and the regular use of the lime-wash brush, emptied the hospital wards of fever patients. Surface cleansing at Balaklava, and regular scavenging both the shores and water of the harbour; covering the shallow graves with gravel and earth; scavenging the camp, and daily disinfecting all latrines, soon reduced the British army mortality below home or barrack life and service. The French neglected these things, or blundered in their execution, as the 5000 deaths per month in the hospitals on the Bosphorus, from hospital and camp fever alone, during the last three months of the war, testify. That certain diseases are contagious, such as scarlatina, measles, small-pox, &c., few will deny. That plague and cholera are equally contagious many doubt. Sanitary works and regulations of a very primitive and simple kind can certainly check the contagibility of cholera, as witness the experience in Newcastle-upon-Tyne and Tynemouth, in London, in many other English towns and districts, and in the British hospitals and camps throughout the Crimean campaign. The lesson taught by experience ought to be this:--Let the Board of Health at Marseilles cleanse the town, cause all the foul rooms to be ventilated and lime-washed, disinfect the foul cesspools and sewage, and cut it off by “interception” from the harbour and docks, and they may bid defiance to plague from any quarter. It may be imported in silks, &c., but it will not spread. Let there be a sanitary staff for the harbour, and another for the town, armed with brooms, barrows, and lime-wash brushes, in place of sidearms and muskets, and persons may land at once to go about their business, and merchandize may be forwarded to its destination without fear of consequences. During periods of epidemics there can be cholera without dirt; improper food and mental and bodily exhaustion may bring on isolated cases; but to have cholera rampant there must be numbers of human beings fouling air, earth, and water, and habitually living contrary to known sanitary laws and entirely neglecting sanitary precautions. CIVIL ENGINEER. _August 14, 1858._ NOTE 7.--_Mud, Water, and Air._