Basalt beds merit a particular attention, both as regards themselves and the kind of earth which surrounds or covers them. It must be noticed if they are divided in irregular masses, tables or prisms, and what is their arrangement. It be must remarked if they contain the remains of organised bodies, and care must be taken to take samples in their different states, also of the matter on which the basalt rests. It must be certain above all that there is no intervention of scorified matter, or beds of an earthy appareance, to which the Germans give the name of Wakke, and which are proved to be of volcanic origin. The rocks named trachytes by M. Haüy merit the same attention. They are distinguished above all by primitive porphyries, intermediate or secondary, by the absence of quartz and the presence of pyroxène or titanimmed iron.
Whatever may be the nature or age of the soil one sees, it is most important to collect samples of rocks the most common and most abundant which constitute the bulk of the soil: the study of the varieties of subordinate beds and accidental matters of all kind, should be secondary. In general the appearance of the constitution of the locality must be considered if one would proceed usfully to choose the samples destined to represent them; the choice would be easy if one would establish a rule never to quit a declivity, a mountain, a country even, without having made the section (geologically). We should add that these sections should be the principal object in the labours of the geological traveller.
Too large samples must not be taken, samples of 10 to 8 centimètres, by 3 or 4 of thickness, are sufficient. Larger samples must not be taken unless they contain the remains of organic fossils, such as animal skeletons. To pack these samples, they must be covered with fine paper; above this paper they will put the ticket or note of bearing or latitude, then a second fine paper that will be surrounded with tow, and all will be enveloped in grey paper. These samples will then be put in a box, placing them upright and in successive beds, as close together as possible, and filling the interstices with cut paper or tow, in a way to form a mass that nothing can derange. No space must be left between the last bed and the cover. The box must be tarred to avoid humidity.
The merit of geological collections being principally in the knowledge of local circumstances in which each sample is taken, it is indispensable to join to these collections well-arranged catalogues. They will repeat the numbers of the samples and directions written on the labels; all details should be inserted which may give a complete idea of the strata which have been observed, and sketches and drawings taken on the spot should be placed either in the margin or the body of the books. It would be well to have duplicates of the catalogues. One of them pressed between two pieces of board well tied, should be placed on the top of one of the boxes, the other should be adressed directly to M. Vattemare.
CHAPTER II.
BOTANY.
The botanical riches of the museum are composed—1o Of living vegetables cultivated in the garden—2o of the collection of dry plants or herbals, of the different parts of plants dried and in alchool, such at woods, fruits, etc. And of all the produits of the vegetable kingdom that are capable of preservation—3o of the collection of fossil plants.
Living plants.
To promote the progress of science, agriculture and horticulture, it is important to collect in a central garden, like that of Paris, the greatest number of living plants possible.