a considerable influence over the well-being of humanity, and especially over its weaker or more sensitive members. Hence it is that 'change of air' has come to be recognised as a most important salutary and curative agency.

There are few persons who are not sensible of the tonic influence of 'change of air,' and few whose period of active life might not be prolonged by a suitable recognition of the value of its restorative power.

It is not my intention, nor would it be possible in these few pages, to attempt to discuss all the questions which arise in connection with the subject of change of climate, more especially as I have had occasion to examine the most important of these fully elsewhere;1 but I shall content myself with calling attention to a few considerations bearing on this subject which may appropriately occupy our minds at this moment.

And first of all I propose to call attention to the advantage of 'change of air' from town to country.

I was reminded a short time ago by a colleague that a well-known physician of this city was accustomed to say that he knew 'no place so good as London to live in for ten months in the year, and no better place for the other two'!

Certainly I should be little disposed to write in dispraise of London, for there are few great cities that possess such remarkable advantages. Our extensive parks have been compared to 'prairies,' and they penetrate to the very heart of London.

A wide river, a great open air as well as water way, with a magnificent embankment along a great part of its course, flows through its midst—a wholesome and purifying agency; and now that Constitution Hill is to be devoted to public use, it will be possible to drive from Ludgate Hill in the City to the Great Western Terminus at Paddington, through what may be called open pleasure-grounds nearly the whole of the way, viz. from Blackfriars to Westminster Bridge, along the Embankment, through Birdcage Walk to Buckingham Palace and Constitution Hill, and from Constitution Hill through Hyde Park to Paddington.

I suppose there is not a capital in Europe that can boast a similar privilege.

If it were not for the too frequent presence of fog, the atmosphere of London—of a great part of London-would no doubt be, for a great city, exceptionally pure. And it may be as well to point out that what it is customary to call London fog' is not quite correctly named or properly understood. London, while it undoubtedly gives some special properties to its fog, has but little to do with originating it. The real and essential basis of a London fog is a blown by the direction of the wind on to this city.

sea or river mist, London lies but

Vide the author's work on Climate and Health Resorts, new edit.

a short distance from both our east and south coasts. On the east there is nothing but low-lying country between it and the mouth of the Thames, nothing to prevent this sea fog being driven by the prevailing wind over the metropolis. When it reaches the city the cloak of watery vapour prevents the regular diffusion and dissipation of the smoke of the city into the surrounding atmosphere, and for a time the sea mist, mixed with London smoke, hangs over us and gives us what we call a London fog-the essential basis of which is water, not smoke.

The same thing can be observed to proceed from a southwesterly direction. I have followed a sea fog, which made it difficult to cross from Ryde to Portsmouth, the whole way to London, where, in the south-western districts and suburbs it became a London fog,' while the atmosphere of the eastern part of the metropolis, the most densely crowded and the most smoky, remained clear. I have approached London from the east coast and found the same conditions. reversed, the eastern districts enveloped in fog, the western districts free from fog. I have left London perfectly clear, and entered a dense fog at Epsom. I have seen a fog so dense and thick at Leatherhead that it was most difficult to find one's way to the railway station, while from Wimbledon on to London it was and had been perfectly clear.

It is quite certain that little can ever be done, while London remains where it is, to make any serious impression on its fogs. If its production of smoke were diminished by one quarter-a wholly impossible problem-it is doubtful if any sensible difference would be made on these fogs as to their unpleasantness, certainly none in their frequency.

But although London, apart from its fogs, enjoys for so large and populous a city an exceptionally pure atmosphere, especially in the best quarters of the town, yet in all large cities the amount of organic impurities in the air is far greater than in that of country districts. It has been calculated by Dr. Angus Smith that in Manchester the air that a man breathes in ten hours contains 37,000,000 spores! The presence of these organic as well as other oxidisable impurities in the air of towns, even if they are not of a nature to be directly harmful to their human inhabitants, yet indirectly deteriorates the quality of the atmosphere by combining with and taking from it a portion of its active oxygen; hence when one who dwells in a large town suffers from any of the numerous morbid states associated with imperfect oxygenation of the blood, a transference to the country, a 'change of air,' is an obvious remedy.

The air of the open country has the great advantage of affording the languid and feeble, or jaded and overworked organism, that allimportant element of life and restorer of vigour, oxygen, in an active and energetic form. What is called ozone is, as is now very generally known, a condensed and more energetic form of oxygen.

Its presence in the air is a test of its salubrity. It is found to be absent in the air of certain places; in sick rooms, in the neighbourhood of substances undergoing decomposition; it is less abundantly present in the interior of large towns than in the open country, it is found in greater amount over green fields and woods than over barren plains or dusty roads, on the seashore than inland, on the tops of mountains than in valleys or level tracts. It possesses remarkable powers of oxidation and disinfection, and its presence in the atmosphere in relatively large proportions indicates a freedom from substances prone to decomposition.

The healthy activity of all the functions of the body is promoted by breathing an atmosphere rich in active oxygen; and when any of these functions are languishing or embarrassed, how important a condition must this be to their recovery.

But the atmosphere of towns gets often positively and grossly dirty. The dust that is raised by a strong wind and blown into our air-passages, as well as into our eyes and ears, is in a large town composed, in part, of most offensive ingredients, often capable, there ean be little doubt, of exciting disease in delicate sensitive persons. I have long been convinced that a considerable portion of the illnesses caused by a prevalence of cold and strong east winds may be traceable to the effect of the pernicious, infectious qualities of the dust that is blown into our air-passages at the time. Imagine for a moment what the dust of a large city must be composed of, mixed up by the eddying wind and carried backwards and forwards from place to place! And yet we marvel how infective diseases are spread abroad!

The air of the open country has then the enormous merit of being relatively clean; and the advantage of living in the clean, pure, tonic air of the country, when it is practicable, must be obvious to all. Those who dwell in London are particularly fortunate in living within very easy access of a number of country resorts charmingly picturesque and eminently salubrious. In Kent, Surrey, Middlesex, Hertfordshire, and in parts of Essex, within twenty-five miles of London, every kind of rural scenery and attractions can be found. Suitable hotel accommodation at a moderate cost is, however, not easily procurable. Indeed, in some of the most attractive localities within forty miles of London there is a remarkable absence of any comfortable hostelry. Convalescent homes for the poor exist in many of these attractive spots, as at Wimbledon, Walton, and Berkhampstead, and the wealthy classes can always obtain what they require, but the middle classthe poorer middle class-are very badly off in this respect.

Another common form in which change of air' is sought is by removal to the sea-coast; and in an island like our own, with so many attractive resorts on our coast to choose from, this is, perhaps, the most popular of all changes.

There is nothing that is new to be said of the tonic and restora

tive properties of sea air as encountered on the sea-coast. Crowded watering-places have, however, dangers of their own which merit consideration. There is the somewhat sudden seasonal strain on their sanitary resources, the overcrowding of lodging-houses, the possibly dangerous encounter with convalescents from infective disease, who have been incautiously and prematurely sent away from home; and more than this, it is certain that the air of some seaside resorts has a distinctly injurious effect on some persons. Disturbances of the functions of the stomach and liver may frequently be observed in some nervous sensitive subjects when they are dwelling on the seashore, and a seaside dyspepsia accompanied by great nervous depression is not a very rare affection. These disturbing influences may, however, often be avoided by those who are sensitive to them, by the selection of a coast resort where they can conveniently live at a little distance from or above the sea. It is in those resorts where the visitors have to live on a level with and literally by the sea, that these unpleasant consequences are especially observed.

But one of the most thorough and complete 'changes of air' is for a dweller inland to take a voyage on the open sea, and I now pass on to notice briefly the so-called 'ocean cure.'

In the first place it may be well to mention the advantages of a sea voyage, as they are generally stated; these are:

1. Perfect rest and quiet, and complete removal from and change of ordinary occupation and way of life; a very thorough change of scene, and perfect and enforced rest from both mental and physical labour.

2. The life in the open air, and the great amount of sunshine to be enjoyed; it is quite possible, under favourable circumstances, to pass fifteen hours daily in the open air; and whenever it is possible the traveller by sea is certain to endeavour to escape from the close and sometimes unpleasant atmosphere of a small cabin, into the pure air to be found on deck.

3. The great purity of the air at sea, and its entire freedom from organic dust and other impurities. In this respect it has an advantage over the air of the open country, for the latter is apt to contain the pollen of grasses and other plants, which in some persons excites hay fever and asthma. The air of the cabins may, of course, be contaminated, but the air of the open sea is probably the purest that can be found anywhere.

4. The presence in sea air of a large amount of ozone, as well as of particles of saline matter, more particularly in stormy weather, from the sea-spray, and these may exercise a beneficial effect in certain throat and pulmonary affections on the respiratory mucous membrane.

5. The great equability of the temperature at sea. This refers chiefly to the daily variations, which rarely exceed 4° or 5° F. It must be noted, as we shall see presently, that in a long sea-voyage

very considerable variations of temperature are encountered, and in a swift steamer the transitions are somewhat sudden.

6. The great humidity of the atmosphere and the high barometric pressure, which are considered to exercise a useful sedative influence on certain constitutions. It is said that the temperature of the body averages 1° F. less on account of this sedative effect.

7. The exhilarating and tonic effect of rapid motion through the air; for by the continuous progress of the ship the sea breezes are constantly blowing over it, and the passengers are borne through the rapidly moving air without any exertion of their own. The influence of these currents of air on the surface of the body is no doubt important, acting as a stimulant and a tonic, increasing evaporation from the skin, and imparting tone to the superficial blood-vessels.

To these influences must be added, in the case of long sea voyages, the invigorating effect of the changes of climate experienced in passing through the different regions of the ocean. It cannot, however, be doubted that, although this may have a bracing effect on many, it is often felt to act injuriously by the more serious and sensitive class of invalids.

A great variety of sea voyages are now practicable for invalids and others. There are, in the first place, the short sea voyages or trips in large ocean-going steamers to Madeira or the Canaries and back, to Gibraltar, Malta, Naples, and the various Mediterranean ports; then there are the 'pleasure trips,' with frequent stoppages and landings, now organised at different periods of the year by the P. & O., the Orient, and other companies; there are, in the next place, those voyages of medium length, such as to the West Indies and back, to Brazil and the River Plate, to the Cape and back, to India and back; and, lastly, there are the long sea voyages, by which is usually meant the voyage round the Cape to New Zealand or Australia and back, or the route by the Suez Canal may be taken, or the voyage to India may be extended to China and Japan. Various other voyages of great interest may be planned, but those here enumerated are the most suitable for invalids.

And now comes the very practical question, 'For what kind of invalids' are these voyages to be recommended? All authorities are agreed that the best results from sea voyages are observed in those cases of anomalous nervous affections, unconnected with organic disease, that are induced by overwork, worry, and anxiety, and often associated with disorder of the digestive organs. The entire rest, the constant exposure to the invigorating sea breezes, the open-air life, the total change of scene and entourage, all these influences combined tend to bring back the power of sleeping soundly and of digesting well, and so restore a healthy activity both of mind and body. As these nervous conditions vary greatly, so the kind of voyage appropriate to their several needs varies also: for some, a mere