theoretically deduced is advantageous to science. 
Appendix. 399 
1 
-ceptacle. At every sea-port to which ships are bound with unclean 
bills of health, an apparatus of this kind should be provided, on a 
scale sufficient for the emergency. And on the Continent, similar 
provision should be made, at every barrier which is destined to pre~ 
vent the introduction of contagious diseases.* 
It must be obvious that these precautions offer no security against 
the danger of a contagious disease breaking out in a person who has 
already been exposed to infection, but in whom symptoms of the 
disease have not yet manifested themselves. Risks from this source 
constitute, however, a very small proportion, compared with those 
arising from fomites ; and they may be easily and effectually guarded 
against, by insulating the person supposed to be infected, for a period 
of time exceeding that, during which the seeds of the disease have 
been ascertained to lie dormant in the animal system. Nor is this 
proposal meant to supersede the employment of chemical disinfect- 
ants, especially of preparations of chlorine, in the apartments of the 
sick ; or their application to articles and fabries which sustain no in- 
Jury by exposure to those agents. ; 
I am, Gentlemen, your obedient servant, = Wittiam Henry. 
Notice of the Volcanic Island thrown up between Pantellaria and 
Sciacca. By Wittiam Arnsworts, Esq., M.R.S. L., Member 
of the Royal Geographical Society, &c. . 
[From the Magazine of Natural History, &e.] 
Tue ejection of volcanic masses, or the elevation of the strata of 
the earth above the level of the soil or sea by natural causes, is of 
importance, remotely to all theories of the earth, and proximately to 
the true origin and formation of pseudo and active volcanic rocks 
and of craters of elevation. 
This branch of geological inquiry has received a new impulse from 
the late researches of De Buch and Elie Beaumont, and every cir- 
cumstance which tends to give consistency to opinions more or less 
* No importance is annexed by the writer to any particular form of apparatus; 
Nor is steam preferred, as the vehicle of heat; for.any other reason, than that it 
affords an effectual security against such a temperature as would be injurious to 
the substances intended to be disinfected. If, in the further progress of inquiry, it 
Should be found that any kind of contagion requires a heat not greatly above 212° 
Fahrenheit, it may easily be attained, (the articles being still secure from damage) 
by using steam of higher pressure than that of the atmosphere. 
