During this long and interesting journey, Mr. Loudon visited and took views of nearly all the palaces and large rural residences in the countries through which be passed; and he visited all the principal gardens, frequently going two or three days' journey out of his route, if he heard of any garden that he thought worth seeing. He also visited most of the eminent scientific men in the different cities he passed through; and was elected a member of the Imperial Society Of Moscow, the Natural History Society at Berlin, the Royal Economical Society at Potsdam, and many others. I have often wondered that, on his return home, he did not publish his travels; as the Continent was then, comparatively, so little known, that a narrative of what he saw, illustrated by his sketches, would have been highly interesting. Business of a very unpleasant nature, however, awaited him, and probably so completely occupied his mind as to leave no room for anything else.

I have already mentioned that when Mr. Loudon went abroad, he had a large sum of money lying unemployed in his banker's hands; and with this he was induced, I know not how, to embark in mercantile speculations and underwriting ships at Lloyd's. As he knew nothing of business of this nature, it is not surprising that his speculations turned out badly; and, for more than twelve months, he was involved in pecuniary difficulties. I am unable to give all the details of his sufferings during this period, as it was a subject he never spoke of, and the allusions to it in his memorandum books are by no means explicit. It appears, however, that after having made several fruitless journeys (including one to Paris, in 1815) in the.hope of recovering some part of the property, he was compelled to submit to the loss of nearly the whole; and that his health was very seriously injured by the anxieties he underwent.

About this time (1816), his mother and sisters left the country, and he, having determined that in future they should reside with him, took a house at Bays water called the Hermitage, which had a large garden annexed. His health was now seriously impaired, but his mind always seemed to acquire additional vigor from the feebleness of his body; and, as he was unable to use so much exertion as he had formerly done in landscape-gardening, he amused himself by trying experiments relating to the construction of hothouses, and by having several of different kinds erected in his garden.

In August, 1815, a paper bad been published in the Transactions of the Horticultural Society, by Sir George Mackenzie, of Coul, on the "Form which the Glass of a Forcing-House ought to have, in order to receive the greatest possible Quantity of Rays from the Sun." This form Sir George conceived to be that of a globe, but as it seemed impracticable to make a hothouse globular, he proposed to make the roof the segment of a circle. Mr. Loudon appears to have been very much struck with this paper, but he saw faults in the plan which he thought might be amended, and he tried houses with curvilinear roofs of various kinds, in order to ascertain which was the best. He also tried a house with what he called ridge and furrow glazing; a plan which has since been carried out on a magnificent scale by Mr. Paxton, in the Duke of Devonshire's splendid conservatory at Chats-worth. While these houses were in progress, he wrote a work entitled "Remarks on the Construction of Hothouses, Ac," which, was published in 1817. Shortly afterwards he invented a new kind of sash-bar, of which he gave a description, together with sketches of the hothouses, and details of their construction, in a quarto pamphlet, entitled "Sketches of Curvilinear Hothouses, Ac," which was published in 1818. The profits of this bar he was to have shared with the ironmonger by whom it was sold; but, I believe, he never reaped any pecuniary advantage from it.

He also published, in folio, another work, in the same year, entitled "A Comparative View of the Common and Curvilinear Modes of Roofing Hothouses".

He now seems to have determined on devoting his time principally to his pen; and he began to collect materials for the well-known Encyclopoedia of Gardening. It is probable that the first idea of this work had occurred to him while he was travelling, from the great number of gardens he had seen, and the various modes of gardening that he had found practised in different countries. At any rate, he determined to commence his work with a history of gardening, and a description, of the gardens of various countries, introducing illustrative drawings engraved on wood, and printed with the text, this being, I believe, the first time any engravings, except mere outlines, had been printed in that manner. It was necessary, in order to complete his plan, that he should see the gardens of France and Italy, in the same manner as he had seen those of the North of Europe; and, for this purpose, he determined to set out on another tour, though his health was at that time so very indifferent, that one of his friends, who saw him at Dover, told him he looked more fit to keep his bed than to set out on a journey.

Mr. London, however, was not easily deterred from anything that he had resolved upon, and he proceeded by way of Calais and Abbeville to Paris, where he arrived on the 30th of May, 1819. After seeing everything deserving of notice in Paris, and becoming acquainted with many eminent men there, from the letters of introduction given to him by his kind friend, Sir Joseph Banks, he left, on the 10th of June, for Lyons, in the Botanic Garden of which city, he saw, for the first time, a living plant of the Vallisneria, which bad not then been introduced into England, and which he had only seen in a dry state, in the Hortus Siccus of Sir Joseph. From Lyons he went to Avignon, and then he visited the celebrated fountain of Vaucluse. Afterwards he proceeded to Marseilles, and thence to Nice, from which city he sailed, in a felucca, for Genoa.