Observations, to recalculate.--Send by post to England a complete copy (always preserve the originals) of all your astronomical observations, that they may be carefully recalculated before your return, otherwise a long period may elapse before the longitudes are finally settled, and your book may be delayed through the consequent impossibility of preparing a correct map. The Royal Geographical Society has frequently procured the re-calculation of observations made on important journeys, at the Royal Greenwich Observatory and elsewhere. I presume that a well-known traveller would never find a difficulty in obtaining the calculations he might desire, through the medium of that Society, if it was distinctly understood that they were to be made at his own cost.
Lithograph Maps.--It may add greatly to the interest which a traveller will take in drawing up a large and graphic route-map of his journey, if he knows the extreme ease and cheapness with which copies of such a map may be multiplied to any extent by a well-known process in lithography: for these being distributed among persons interested in the country where he has travelled, will prevent his painstaking from being lost to the world. Sketches and bird'[S-eye views may be multiplied in the same manner. The method to which I refer is the so-called Anastatic process; the materials can be obtained, with full instructions, at any lithographer's shop, and consist of autographic ink and paper. The paper has been prepared by being glazed over with a composition, and the ink is in appearance something like Indian ink, and used in much the same way. With an ordinary pen, with this ink, and upon this paper, the traveller draws his map; they are neither more nor less difficult to employ than common stationery, and he may avail himself of tracing-paper without danger. He has one single precaution to guard against, which is, not to touch the paper overmuch with his bare and, but to keep a bit of loose paper between it and the map as he draws. As soon as it is finished, the map is taken to a lithographer, who puts it face downwards on a stone, and passes it under his press, when every particle of ink leaves the surface of the paper and attaches itself to the surface of the stone, precisely as though it had originally been written there; the glaze on the paper, which prevents the ink from soaking into it, makes this transference more easy and complete. The stone can now be worked with, just as a stone that has been regularly lithographed in the usual manner; that is to say, printing ink may be rubbed over it and impressions may be taken off in any number. It will be observed that the writing on the paper is reversed upon the stone, and is re-reversed, or set right again, in the impressions that are taken from it. The lithographer's charges for furnishing autographic ink and paper, working the stone, striking off fifty copies of a folio size, and supplying the paper (common white paper) for the copies--in fact every expense included--need not exceed ten shillings, and may be much less. If before drawing his map the traveller were to go to some working lithographer and witness the process, and make two or three experiments in a small way, he would naturally succeed all the better. A map drawn on a large scale, though without any pretension to artistic skill, with abundance of profile views of prominent landmarks, and copious information upon the routes that were explored, written along their sides, would be of the utmost value to future travellers, and to geographers at home.
INDEX.
Accumulators.
Advantages of Travel.
Agates for striking sparks.
Agreement with Servants.
Alarm gun.