the Isthmus of Panama.  And the grandeur of this invasion by steam is beyond the reach of imagination.  Thousands of islands, clothed in gorgeous yet delicate vegetation, and enjoying the finest climate, lie scattered like diamonds in a sea on which storms never rage—­each in itself an earthly paradise.  When these islands can be reached at a moderate outlay of time, money, and trouble, may we not expect to see them visited by the curious, and flourishing as seats of civilised existence?  There is reason to believe, that the equable climate of many of them would prove suitable for persons affected with the complaints of northern regions; and therefore they may become the Sanatoria of Europe.  ’Gone to winter-quarters in the Pacific!’—­a pleasant notice this of a health-seeking trip twenty years hence.

It may be reasonably conjectured, that this great and varied extension of journeying round the earth, and in all climates, will not be unaided by new discoveries in motive power.  At present, we speak of steam; but there is every probability of new agents being brought into operation, less bulky and less costly, before twenty years elapse.  Even while we write, men of science are painfully poring over the subject, and giving indications that in chemistry or electricity reside powers which may be advantageously pressed into the service of the traveller.  Admitting, however, that steam will be retained as the prevailing agent of locomotion, we have grounds for anticipating improvements in its application, which will materially cheapen its use.  As regards safety to life and limb, much will be done by better arrangements.  In steam-voyaging, we may expect that means will be adopted to avert, or at least assuage, the terrible calamities of conflagration and shipwreck—­better acquaintance with the principles of spontaneous combustion, and with the natural law of storms, being of itself a great step towards this important result.

One of the latest wonders in practical science, is a plan for cooling the air in dwellings in hot climates; by which persons residing in India, and other oppressively warm countries, may live habitually in an atmosphere cooled down to 60 degrees Fahrenheit, or the ordinary heat of a pleasant day in England.  The very ingenious yet simple means by which this is to be effected, will form the subject of notice in our next number.  Meanwhile, we may observe that the discovery is due to Mr C. Piazzi Smyth, astronomer-royal for Scotland; and if perfectly successful in practice, of which there can be no reasonable doubt, it will have a most important effect in extending European influence over the globe.