In all cases where practicable, specimens of products should be obtained, in order that specialists at home may judge of their industrial or commercial value. For those who may have more leisure for observation, some or all of the following detailed hints may be useful:— MINERALS AND METALS.—It is not necessary to add much here to what has been said under Geology. If the traveller is not himself competent, or has no opportunity to test the value of these products, he should bring home specimens; this, if possible, should be done in any case. Under this section a look-out should be kept for any indication of naphtha, asphalt, or mineral oils. From the commercial point of view the important points are— _Quality._—To what extent are minerals or metals, as gold, copper, iron, phosphates, mixed up with other matter? What is the yield per ton of ore? In the case of coal, how does it burn, and what is the percentage of ash? Next— _Quantity._—Does the substance occur in sufficient quantity to make it worth expenditure of capital and labour? The information must be obtained by personal inspection. Finally— _Locality._—Is the situation of the deposits easily accessible? How are they situated with reference to routes, existing or practicable? and how with reference to ports of embarkation? Could they be worked with the resources available in the country, or would labour and machinery require to be introduced? If worked in the country, is there any neighbouring market for the manufactured products? What are the native processes (if any) of obtaining and working minerals? We must again refer to the section on Geology for further details, and the intending traveller would do well to take a few lessons before he leaves, so as to be able to recognise the most common and useful minerals and the conditions under which they usually occur; he will thus save much time and trouble. VEGETABLE PRODUCTS.—The directions for observation and collection given under the Botanical section should be attended to; and it is important that the traveller should be able to recognise the chief classes of plants, so that specialists may be able to pronounce generally on their utility. _Character of Surface._—The general character of the surface of a country, so far as its vegetation is concerned, should be clearly grasped. What proportion, or, if possible, what area is under forest? what under grass? what desert, or mountain, or marsh, or uncultivable? what under cultivation?