1881. ] Microscopy. 757 
of the main features of a country, its ranges of mountains, rivers, 
etc.,as the chief aids in the. study of geography, which ought, 
therefore, to be under the charge of the physical and mathemati- 
cal teachers, whose sense of form and skill in drawing was far 
better developed than in teachers of philological and historical 
subjects. Dr. Neis, a surgeon in the French navy, has recently 
made a journey in Indo-China, and discovered the source of the 
Dong-nai River in 12° 30’ N. lat., 108° 25’ 15’’ E. long. In 
describing Dr. lleath’s recent discoveries on the Beni, as men- 
tioned in the Naturatist for June, the Proceedings of the Royal 
Geographical Society says: “ As Dr. Heath claims to have been 
the first white man to see the mouth of the Madre de Dios, it 
may be interesting to remind our readers that in a paper’ read 
before the society on February 25, 1867, our honorary corre- 
sponding member, Professor Raimondi, informed us that in March, 
1861, Don Faustino Maldonado, of Tarapoto, in Peru, with seven 
companions, had descended the Madre de Dios into the Mamoré, 
and that though the leader and three others were drowned in the 
dangerous rapids called the Calderao do Inferno, the remainder 
continued the voyage down the Madeira into the Amazon.” 
correspondent of the London Azheneum has discovered in a copy 
of the Lyons edition of the “ Cosmographia” of Hylacomylus, 
published in 1514, a map which is the earliest known upon which 
the name America appears. The new world is represented by a 
large island in the “ Oceanus Occidental,” and across it is en- 
graved “ America noviter reperta.” Heretofore it has been sup- 
posed that the most ancient map on which the name appears is 
the “ Typus Orbis,” printed at Vienna in 1520. 
MICROSCOPY.’ 
Microcrapuic TrAciINGs.—In many physiological tracings it has 
been thought that seme of the curves supposed to be of signifi- 
cance may possibly have been the result of oscillations of the 
lever, It seemed, therefore, to M. Marey, desirable to remove 
this doubt, and ¢o demonstrate the fidelity of the instruments by 
showing that identical tracings may be obtained by other instru- 
its rapid move- 
ment, go too far before the friction arrests it. If, however, the 
amplitude of the movement is reduced to one-tenth (qo), the 
effect of the momentum of the lever will be reduced to one- 
hundredth (rds, the square root) of that which it possessed in the 
Ormer case. But in order to preserve the form of the trace, the 
‘Surface on which the lever writes must move very slowly, not 
More than one (1) millimeter per second. The details of the 
UR. G. S. Journal, Vol. xxxvu, p. 137- : 
This department is edited by Dr. R. if. WARD, Troy, N. Y. 
