GEOLOGY AND MINERALOGY. 135 



be brought home adhering to their natural situations ; and un- 

 less the species of the tree on which they grow is known to 

 the traveller, a specimen branch should be imported at same 

 time. 



It is of consequence also, to observe which way climbing and 

 parasitical plants bind round the stems to which they adhere, 

 that is, to ascertain whether they are dextral or sinistral plants. 

 The naturalist must suppose himself in the place of the stem, 

 placing himself with his face turned towards the south pole, 

 and then mark whether they ascend to the right or left. Those 

 whose head twists in the same direction which the sun appears 

 to move in, are dextral plants. 



GEOLOGY AND MINERALOGY. 



Every mineral from the most common clay or sand, to the 

 gem, ought to be collected. 



Specimens of rocks, such as granite, porphyry, limestone, 

 slate, &c., should, if possible, be broken from fixed rocks, 

 and not from loose masses, which are generally decayed. In 

 selecting the specimens, one set ought to represent the differ- 

 ent varieties of appearance presented by the rock in the fresh 

 state ; another the rock in its different states of decomposition. 

 It is not sufficient for the geologist to content himself with 

 possessing a simple specimen of any mountain rock. For he 

 will find that they present considerable variety of structure in 

 different districts, and these are very interesting to be brought 

 together for comparison. By an accumulation of these, we 

 may be assisted in coming to certain conclusions concerning 

 their primary formation, and other geological facts. 



When the specimens of simple minerals or rocks contain 

 crystals, they ought to be wrapped in fine paper, and then in 

 cotton, and afterwards in several folds of strong wrapping- 

 paper. 



The specimens of rocks ought, if possible, never to be less 

 than four inches square, and one inch in thickness, and of a 

 square form. As soon as they have been prepared, they should 

 be labelled, and put in several folds of strong wrapping-paper 

 to prevent friction. When paper cannot be procured, moss, or 

 other soft vegetable substances, may be substituted for it. 



M2 



