1820.] Use of Gauze Veils cs Preservatives from Contagion. 13 

 truth," experience, which he so confidently challenoes. I will 

 now pursue the arguments of M. Rigaucl de I'lsle. "■ iMiasmuta" 

 he says, " possess such a graviti/ that they can never rise in the 

 atmospheiv unless assisted by a Tighter body, which carries titem 

 into it" In support of this, he says, the air which is very 

 unhealthy at Montalto, Corteno, and along all that coast, 

 stretching to the south as far as Terracina, becomes salubrious 

 on Mount Argentaro, which rises above Orbitello. The villages 

 of la Tolfa, and the habitations situated above C^ivita Vecchiaon 

 the Cimic hills, afford a very agreeable and healthy abode, 

 though situated in the centre of that region of desolation. The 

 same is the case when we rise above the village of St, Felice on 

 the mountain of Circe to the palace of Theodoric above Terra- 

 cina; to.the villages of Segga and Sermoneta, perched perpendi- 

 cularly above the Pontine marshes on the rocks of the Lepiae 

 mountains ; also at Monte Fiascone above the lake of Bolsena, 

 above the villages of Valentano, Capo di Monte, Martha, &c. 

 A little further eastward, on the insulated rock of St. Orestes, 

 the inhabitants of the village, which is built on its side, enjoy 

 the best health ; if they descend, disease attacks them, and 

 common fevers make their appearance ; and a httle lower down, 

 for instance at Sandreva, they will have putrid fevers ; and still 

 lower down, tiiey will die. The observations of some eminent 

 travellers support these remarks. 



" Miasmata," he continues, " have no smell by which they 

 can be distinguished. They may be separated from the odorous 

 substances with which they seem' to be most intimately blended." 

 Of the peculiar odour emitted by stagnant waters, he adds, it 

 has something disagreeable and sickly, which seems to warn us 

 not to approach places: where it is perceived ; it may, however, 

 be inhaled without any ill effect in certain seasons of the year. 

 I have myself been several times exposed to it. In 1810 and 

 1811, in passing the numerous ponds which cover the sea coast 

 of the ecclesiastical state, at Maccharese, Ostia, Foliguano, ia 

 the Pontine marshes, which I have repeatedly traversed in 

 various directions, I have always perceived this peculiar smeli, 

 without sustaining any inconvenience from it. The following 

 year, on the contrary, on a very hot day in the beginning of 

 September, among the ponds of Vauvert, between St. Giles and 

 Aigufcs Mortes, in Languedoc, I was suddenly seized with nausea 

 aud a feelmg of sickness, which lasted several days, though I 

 ro-marked at the time tiiat no kind of odour was emitted by the 

 marsh. He asserts, from experience, that " it is much more 

 duiigeroiis to inhale bad air in the night than in the day time. 

 Ail the hours of the day or of the night are not attended with 

 equal risk. The least critical niomeiit is when the heat is 

 greatest and the sun highest above the horizon. The most 

 dangerous is that which accompanies the setting and that v/hich 

 precedes the v\^\xig of the sun." TJiis observation, which applies 



