JaNuaRY 4, 1917] 
shale and a thin seam of coal, neither being of any 
value. The remainder of the Cenomanian, above 
the Nubian Sandstone, contains many fossils, 
and includes some beds of oil-bearing marls, not, 
however, valuable. The limestones above these 
represent the Turonian and Santonian, but are not 
nearly so rich in fossils as the underlying beds. 
Eocene strata succeed, chiefly clays, and to them 
sandy clays and grits representing the Miocene, 
both being fossiliferous; the coastal deposits are 
Pleistocene and Recent. The rather frequent 
dykes and sheets of basalt are probably Miocene, 
to a later part of which belong the numerous 
faults. In the neighbourhood of these the strata 
are often much tilted, but otherwise are not far 
from horizontal. In one district occur associated 
ores of iron and manganese, which are now being 
worked. 
The climate is temperate, dry, and very healthy. 
Fic. r.—View of the ‘‘Seil” in Wadi Abu Qada, February 14, 1913. 
From ‘‘ The Geography and Geology of West-Central Sinai. 
In winter the frequent north winds cause sharp 
frosts in the higher districts, but on the coastal 
lowlands it is often warm and misty. The rain- 
fall is very slight, generally not more than an 
inch in a year. But a heavy rainstorm may occur 
every four or five years, when the water, running 
rapidly off the steeply sloping sides of the valley, 
gives rise to a sudden flood which sweeps every- 
thing before it. Dr. Ball was fortunate enough 
to secure a photograph showing the front of one 
of these torrents, of which Fig. 1 is a reproduc- 
tion. One such flood in 1867 swept away an 
Arab encampment in Wady Solaf, drowning forty 
persons, with many camels, sheep, and cattle. 
But at other times the only sculpturing agents are 
wind-blown sand and strains set up in rock sur- 
faces by changes of temperature, both, as Dr. 
NO. 2462, VOL. 98] 
NATURE 
353 
| Ball describes, of considerable importance. But 
it is scarcely possible that the deeply carved valleys 
_can be the result of existing conditions; probably 
| they were produced when the rainfall was much 
greater, its later part corresponding with an age 
of ice in our own islands, when a great lake 
_ occupied the Jordan valley. 
There is, as a rule, little vegetation or animal 
life. Of what is found Dr. Ball gives particulars. 
In short, we are indebted to him for a very full 
and clearly written account of the geology, geo- 
graphy, and natural history of this part of the 
Sinai Peninsula, the value of which is enhanced 
| by many illustrations—photographs of scenery, 
| drawings of fossils, and a coloured geological 
_map. Both he and the Survey may well be con- 
gratulated, especially in existing circumstances, 
on the publication of so excellent a memoir. 
T. G. Bonney. 
THE PHYSIOLOGY OF FATIGUE. 
NE effect of the war has been to increase the 
strain thrown upon industrial workers as a 
result of longer working hours and insufficient 
holidays, and efforts are being made not only to 
counteract the ill-effects of extreme physical 
fatigue, but also to devise means for the recog- 
nition of fatigue and to study the conditions under 
which it occurs. The latter aspect of the question 
is dealt with by Prof. Kent in a report on indus- 
trial fatigue recently issued by the Home Office.? 
For this ‘(purpose Prof. Kent employed as tests 
of the occurrence of fatigue, in the first place, 
alterations in the length of the reaction time and 
in the visual and auditory acuity of the worker, 
and, in the second place, the influence of overtime 
| upon the actual output of the worker. A number 
of workers were examined, the observations in 
| some cases extending over several weeks. 
The general conclusion drawn from the inquiry 
is that overtime—that is to say, a longer working 
day—leads to increased fatigue, this being mani- 
fested both by the physiological tests employed 
and by its effect upon the efficiency and output 
of the worker. The evidence furnished by the 
| physiological tests is, however, quite uncon- 
vincing ; not only do the figures obtained by these 
tests vary enormously from day to day, but in 
some instances the tests indicate that the workers 
are less fatigued in the evening than in the morn- 
ing, and less tired after a long working day than 
after a short day. Further, the purely subjective 
character of these tests renders them liable to be 
influenced by many causes other than fatigue, 
and they appear to have little or no value as an 
| index of general fatigue. 
The observations on the effect of overtime upon 
the daily output of work are of interest because, 
in some instances, the output of the same 
workers was noted during weeks when over- 
time was worked and during weeks when no over- 
time was worked; the total output was unaffected 
1 Second Interim Report on an Investigation of Industrial Fatigue. By 
Prof. A. F. Stanley Kent. [Cd. 8335.] (Issued by the Home Office.) 
price 1s. 6d. 
