MEMORANDA IN REFERENCE TO THE NATURAL HISTORY OPERATIONS. 9 
6. Great care will be observed to place the magnets in their proper positions in the cases, 
and not to touch them with iron or steel. The observations must be made ata distance of at 
least 300 paces from the wagons, to avoid the influence of the iron tires. Observers will care- 
fully divest their clothing of all substances having magnetic attraction, 
MEMORANDA IN REFERENCE TO THE NATURAL HISTORY OPERATIONS. 
PREPARED BY 8. F. BAIRD, UNDER THE DIRECTION OF THE SMITHSONIAN INSTITUTION. 
The general principles to be observed in making collections of natural history in a new 
country, or one previously unexplored, is to collect everything which may present itself, from 
time to time, subject to the convenience or practicability of transportation. The number of 
specimens to be secured will, of course, depend upon the dimensions, and the variety of form or 
condition caused by the different features of age, sex, or season. 
Where a small part only of the specimens collected can be taken along, such species should 
be selected as are least likely to be procured in other localities or at other opportunities. Among 
these may be mentioned the reptiles, fishes, soft insects, &c.; in fact, all such as require alcohol 
for their preservation. Dried specimens, as skins, can be procured with less difficulty, and are 
likely to be brought in by persons not specially interested in scientific pursuits. 
The description of various processes, to be employed in the collection and preservation of speci- 
mens of different kinds, will be found detailed at sufficient length in the ‘‘ Directions’’ published 
by the Smithsonian Institution, and in the Admiralty Manual of Scientific Enquiry. 
In collecting specimens of any kind, it will be important to fix, with the utmost precision, 
the localities where found. This is especially desirable in reference to the fishes, which occupy 
a very intimate relation to the waters in which they live. 
The smaller quadrupeds, of the size of a mouse, may be preserved entire in alcohol. Larger 
kinds should be skinned, and the skins thrown into alcohol, or coated inside with arsenic and dried. 
The latter course may be indicated for species larger than a prairie dog or hare. The skulls 
of the small kinds may be left in the skins; those of the larger should be removed, taking care 
to attach some common mark by which they may be again brought together. Large animals, 
of the size of a wolf and above, may, for greater convenience, be skinned after the method pur- 
sued by butchers, by skinning the legs down to the toes, and cutting off at that point. The 
skins need not be sewed up, as is directed for the smaller kinds, but rolled up into bales, after 
applying an abundance of arsenie and drying. 
It will be very important to procure the skeletons, and, at all events, the skulls, of all the 
species of animals, in sufficient numbers to include all the variations of age and sex. These 
may be roughly prepared by cutting off the flesh and drying in the sun. 
As the expedition will pass through the breeding-ground of many species of birds whose nidi- 
fication and eggs are not known, attention should be paid to securing abundant specimens of 
the nests and eggs. As far as possible the skin of the bird to which each set of eggs may belong 
should be secured, and have a mark attached common to it and the egg. 
The larger snakes should be skinned, as indicated in the ‘‘Directions,’’ as thereby they 
will occupy much less space than otherwise. The smaller specimens preserve entire, together 
with the lizards, salamanders, and small frogs. All of these that can be caught should be 
secured and preserved. 
The head, legs, with feet, the tail, in fact the entire skin of turtles, may be preserved in 
alcohol ; the soft parts then extracted from the shell, which is then to be washed and dried, 
Every stream, and, indeed, many localities in each stream, when passable, should be explored 
for fishes, which are to be preserved as directed in the pamphlet. For these, as well as the 
other alcoholic collections, the lino bags will be indispensable. 
2f 
