American geologists in the advance of this science. There has been
through the century a gradual movement of what might be called the
center of gravity of geological research westward, until now, at its
end, the most productive activity is here in America. This is not due
to any superiority of American geologists, but to the superiority of
their opportunities. Dana has well said that _America is the type
continent of the world_. All geological problems are expressed here
with a clearness and a simplicity not found elsewhere. We must add to
this the comparative recency of geological study in this rich field. In
Europe the simpler and broader problems are already worked out, and all
that remain are difficult problems requiring much time. In America, on
the contrary, not only are all problems expressed in simpler terms, but
many great and broad problems are still awaiting solution. For these
reasons the greatest activity in research, and the most rapid advance
during the next century, will probably be here in America.
"SALAMANDERS" AND "SALAMANDER" CATS.
BY NORMAN ROBINSON.
In many places in the extreme Southern States, especially in what is
locally known as the "piney woods," one of the most notable features
is the constantly recurring mounds of yellow sand which everywhere dot
and, it must be confessed, disfigure the monotonous landscape. These
piles of earth are usually nearly circular in form, fairly symmetrical
in contour, from six inches to two feet in diameter, and, save where
they have been beaten down by rain or winds or the trampling of cattle,
about half as high as they are broad. Often these sand heaps are
pretty evenly distributed, sometimes so thickly as to cover at least
one fourth of the soil surface. If you ask a native the cause of
this singular phenomenon, which you will perhaps at first be disposed
to consider a kind of arenaceous eruption which has somehow broken
out on the face of Nature, your informant will sententiously reply,
"Salamanders!"
All this disfigurement is indeed the work of a curious little rodent
popularly so named and about the size and color of an ordinary rat.
He is never seen above ground if he can possibly help it. He digs
innumerable branching underground tunnels at depths varying from one to
six feet, and these mounds of sand are simply the "dump heaps" which,
in his engineering operations, he finds it necessary to make.
[Illustration: "SNAP-SHOT" VIEW OF A LIVE "SALAMANDER."]
After carrying the excavated earth to the surface this cautious little
miner takes the greatest pains to cover up his tracks. No opening into
his burrow is left. How he manages to so carefully smooth over his
little sand mound and then literally "pull the hole in after him" is
as yet unexplained. The work is mostly done at night, when observation
is especially difficult. Sometimes, when he is a little belated and
the early morning twilight admonishes him that it is "quitting time,"
he gets in a hurry and slights his work. Then a little depression at
the top of the mound tells where he has made a hasty exit. Ordinarily
the rounding out of the sand pile is as deftly done as though it had
all been managed from above. Indeed, the feat actually accomplished by
this little underground builder appears more puzzling the more it is
considered. The most skilled human engineer would confess his inability
to thus pile up a mound of loose sand, go down through it, leave
the top perfectly smoothed over, and, with no supports save the sand
itself, to so fill up the passageway above him as he went down that not
the slightest mark should be left to indicate his pathway of retreat.
Even if you dig into and under one of these sand mounds you will find
very little to betray the builder's whereabouts. It is seemingly all
solid earth, and unless you know exactly when and where and how to
dig you will probably give up the search in disgust, with your labor
and your backache but no "salamander" hole for your pains. Indeed,
the cunning of this little rodent in hiding his burrow is quite as
conspicuous as his skill in digging it. "Strategy" is his strong
point. If by any chance you come upon his burrow it is probably an old
abandoned one that is closed up and leads nowhere. The chances are ten
to one that his real burrow is rods if not furlongs away.
Provided you can find the last mound he has built and not more than
four or five hours have elapsed since its completion, by digging
diagonally to the right or left, at the distance of a foot or so, you
will have a fair chance of encountering his burrow. He is probably near
by, resting from the severe labors of the previous night. If you give
him time to get his nap out and finish his job, your wiser plan will be
to stop hunting and digging a little before you begin.
Why this little underground dweller should be called "salamander" is
one of those mysteries of popular nomenclature which is seemingly
inexplicable. There is certainly nothing in the habits or appearance of
the animal to suggest the fabled fireproof batrachian. Like some other
lovers of darkness, he has quite a number of _aliases_ by which in
various portions of the South and West he is known. "Gopher," "pouched
rat," "hamster," and "muelos" are some of the titles by which he is
locally known. "Salamander" appears to be the most generally accepted
one.
This enterprising little rodent belongs to an ancient if not honorable
family. By naturalists he is generally known as "pocket gopher," and
is classed among the _Geomyidæ_. Some fifteen known species have
been recognized, with possibly more to hear from, and with a habitat
extending quite across the continent. The Florida species is probably
_Geomys tuza_ (Ord.), and though not as large as one or two others, is
quite the peer of any of his cousins in enterprise and ability to look
out for himself.
The illustration given is from what is probably the only photograph of
a living "salamander" ever taken. Mr. Geomys is not a model "sitter."
No unwilling candidate for the "rogues' gallery" has more decided
views on the subject of having his picture taken. In a general way,
it may be said that he doesn't pose for anybody. Precisely how this
prejudice was finally overcome it is needless to state. Perseverance
and "snap shots" were too much for our recalcitrant rodent. In the
matter of "looking pleasant" it must be conceded that Mr. Geomys was a
little intractable.
[Illustration: "DUMP HEAPS" OF THE "SALAMANDER."]
The fore legs and feet of the "salamander" are worth studying. They
remind one somewhat of those of the mole, but are more stoutly built,
with much longer claws, and are evidently designed for harder tasks.
They are controlled by powerful brachial and pectoral muscles, and,
as we shall see, are not only special tools adapted to special and
difficult work, but work which requires an enormous expenditure of
physical force.
The engineering problems which this little troglodyte has to solve are
far and away ahead of any that the New York Rapid-Transit Commission
has to deal with. It is very much as though a single miner were placed
over in Hoboken, a hundred feet below the surface, with instructions to
tunnel under the Hudson River with no tools except his hands, without
a chance of seeing daylight until he reached it on the New York side,
and with the added conditions that all the excavated earth should be
carried out at the eastern opening of the tunnel, and finally that he
should obliterate all marks of his work and, as he retreated into his
tunnel, pack the exit shaft above him so tightly and so deftly that it
is impossible to trace its course!
How our little fur-coated engineer solves all these problems is as
yet a mystery. We only know that he does it. He has a steam engine in
his shoulders and shovels for hands, but his exact methods of using
them is as yet largely a matter of conjecture. Only two plans of
operation would seem to be possible. One would be for the "salamander"
to first carry the excavated earth all to the rear into some portion
of his already finished tunnel, and finally, when the outward exit is
completed, to carry it back again and deposit it on the surface. This,
of course, involves a double transfer of all the earth removed. It is
more likely that the "salamander" first forces a narrow passageway
along the line of his future tunnel in a way similar to that pursued
by the mole. The latter animal has the advantage of working near
the surface, and the earth always yields along the line of least
resistance, which of course is upward. Four or five feet down there
is no such line, and the amount of force required to push the ground
aside must be something enormous. When the "salamander" comes to the
upper air the work of excavation and enlargement begins. He then piles
upon the surface all the earth that he can not use in obliterating his
upward passageway. As the writer has frequently observed fresh sand
mounds hundreds of feet from any others, he is inclined to believe that
this is the real method pursued.
The exceeding care which the "salamander" takes to leave no opening
into his subterranean home arises, no doubt, from his horror of snakes.
In this respect no woman can surpass him. His antipathies to reptiles
are probably the accumulated embodiment of hundreds of centuries of
ancestral experience. He is aware that these hereditary enemies of his
race are of a very investigating turn of mind, and put in a good deal
of spare time when awake in crawling into and exploring any tempting
hole they may discover. And so Mr. Geomys, like the sensible fellow
that he is, not only takes good care to shut and lock his front gate
every time he is compelled to go through it, but he blocks up the whole
passageway and does his best to convince trespassers that it is all a
mistake to suppose that there ever has been any roadway leading to his
underground home.
Indeed, it is by taking advantage of this morbid antipathy to intruders
and daylight that our little underground dweller is usually caught. If
by skillful digging a recently formed burrow is reached, one may be
reasonably certain that in from five to ten minutes Mr. "Salamander"
will be on hand to see what has happened and to repair damages. A
shotgun kept steadily aimed at the opening, and with a quick pull on
the trigger the instant the slightest movement in the sand is seen,
"fetches" him every time. Another very successful method is to place
a strong trap right at the opening into his burrow. In making repairs
our "salamander" is in too big a hurry to look very carefully where he
steps, and so is quite likely to blunder into the trap. He is always
caught, however, by one of his legs, and if left any length of time
is quite apt to gnaw off the captive limb and thus make his escape.
Spartan bravery or love of freedom surpassing this would be hard to
find.
The food of _Geomys bursarius_ appears to be exclusively vegetable.
Native roots and root stocks, cones and bulbs, together with the root
bark of various trees, are eaten by him, and sometimes in a very
annoying way. Orange trees are peculiarly liable to his attacks. He
gnaws through and around the tap root as near to the surface as he can
without disturbing it or in any way calling attention to his work, and
not infrequently he continues his depredations until every root of any
size is eaten off. This, of course, means the death of the tree.
From the "salamander" point of view, however, the greatest food
"bonanza" of all is a sweet-potato patch. "A 'possum up a 'simmon
tree" or a "pig in clover" is not more alive to the delights and
advantages of the situation. He not only eats all he can stuff, but
invites his relatives and friends. Nor is this all. He has learned
that in autumn sweet potatoes are liable to suddenly disappear, so he
"takes time"--and the potatoes--"by the forelock," and packs them away
in liberal measure in his burrow for winter use. So well understood
are the ways and weaknesses of this underground marauder that any
suspicious mound of earth in a sweet-potato field is the signal for an
active campaign of extermination, which ends only in the intruder's
flight or death.
The "side pockets" of the "salamander" have already been referred to.
They are undoubtedly a great convenience to their owner in carrying
food and possibly other things. The capacity of these cheek pouches is
about sufficient to give room for a pigeon's egg. They are, however,
quite extensile, and can readily be made to hold three or four times
this amount. Indeed, the skin and underlying connective tissue are so
elastic that these pockets can readily be turned inside out. It is
claimed that the "salamander" employs his handlike fore feet to fill
and empty these receptacles, using the right foot for the left pouch,
and _vice versa_. A gentleman in Florida recently assured me that by a
lucky thrust of a spade he once killed one of these mischievous rodents
as he was in the very act of cutting off the roots of an orange tree.
The cheek pouches of the culprit were filled with fragments of bark
which he had gnawed off, doubtless to be stowed away in his burrow.
Why, in a climate where there is almost no winter, where there is
very little interruption to vegetable growth and the food supply
is practically unlimited, provisions should thus be stored away is
somewhat difficult to explain. It is not impossible that it is simply
the survival of an ancestral habit acquired during the Glacial period.
Or it may be that, like the dog, the "salamander" finds the flavor
of old and well-seasoned food more to his taste. All that can be
positively affirmed is that this wise little rodent does, occasionally
at least, thus _caché_ his food supplies.
One of the most curious results of the existence and habits of this
elusive little burrowing rodent is the development of a new and
peculiar breed of _Felis domestica_, called "salamander" cats. Ordinary
tabbys do not understand or admire the ways of _Geomys bursarius_,
or, for some other good and sufficient feline reason, do not include
him in their game list. The variety of cats in question, which, so
far as the author knows, is confined to Florida, appears to have been
developed spontaneously and with very little if any human agency, and
is noted for its special skill in catching "salamanders," as well as a
decided liking for the sport. Any Mrs. Tabby of this breed, especially
if she has a family to provide for, is up betimes in the morning. The
particular object of her pursuit is a remarkably early riser, and
finishes his day's work before most people have begun theirs. So if
there is a convenient fence around the grounds she proposes to hunt
she mounts it with the first peep of day, and, with a sharp eye to
landward, starts on her tour of observation. Any fresh pile of sand
is closely scrutinized. The slightest movement there brings her to
the mound with a spring, and she is at once crouching behind it; so
when Mr. Geomys comes up in a big hurry with his next load of sand he
finds somebody to meet him that is in a bigger hurry still, and so the
unsuspecting victim is borne off in triumph.
An estimable lady of the writer's acquaintance who owned one of these
"salamander" cats, with a single juvenile pussy to provide for, kept
an accurate account of the number of these rodents which she saw this
industrious mother cat bring to her offspring in a single month. The
number was thirty, and as the month happened to be February this gave,
of course, two more than a "salamander" a day.
One other curious observed feature of this new variety of cats is their
want of fecundity. The mother tabby seldom has more than one kitten
at a birth. The writer once owned a fine female of this breed that
scrupulously adhered to the traditional habits of her race.
This particular pussy, like the rest of us, had her family troubles.
Her one kitten--probably from its mixed parentage--was always inclined
to rebel at the "salamander" diet. There was something amusing to a
degree and suggestively human in the old cat's methods of discipline.
When she had succeeded in catching a salamander she would always first
bring it and lay it down before her mistress, to make sure of the
praise and the petting. Then, with a motherly "_meow_," she would call
her kitten. That frisky little youngster was always quite ready for his
breakfast, but showed a decided preference for the "maternal font."
Then the old cat would give him a "cuff" that would send him spinning.
Then she would take up the "salamander" and put it down before her
hopeful offspring with an air that said as plainly as words could do:
"There, now! Eat that or go hungry!" Then her mother love would get the
better of her and she would go to licking and petting her disobedient
baby, and it would usually end in the kitten's having its own way
and satisfying its hunger with milk from the "original package." By
persistence and the force of example the old cat finally succeeded in
accustoming her offspring to what she evidently thought the orthodox
diet of her race.
The writer is quite well aware of the intrinsic difficulties involved
in the spontaneous development of any new variety of cats. Still, such
branching of types has occurred in the past, and of course is possible
now. When his attention was first called to the matter he was inclined
to consider it merely an instance of animal education. A fact that came
under his personal observation seems, however, hard to reconcile with
this or any theory that does not concede the hereditary transmission of
acquired habits and tastes.
A kitten of the breed of cats in question was taken when very young and
reared nearly a mile away from its mother. When grown it developed the
same skill in hunting "salamanders," and the same love for the sport as
that for which its mother was celebrated.
Dogs, of course, have long been noted for the readiness with which
acquired knowledge, habits, and tastes manifest and perpetuate
themselves in hereditary forms. The setter, pointer, collie, St.
Bernard, and other well-known breeds will occur to everyone as
illustrating this psychic plasticity. Doubtless the cat brain is
somewhat less impressible, but there would seem to be good reasons for
including it among the educably variable types.
WHAT MAKES THE TROLLEY CAR GO.
BY WILLIAM BAXTER, JR., C. E.
III.
NOTE.--Figs. 28 and 32 are reproductions of photographs kindly
furnished by the General Electric Company, while for the view of car,
Fig. 30, we are indebted to Colonel N. H. Heft, chief electrical
engineer of the New York, New Haven, and Hartford Railroad.
Although the electric railway has been introduced throughout the
civilized world with the most remarkable rapidity, replacing cable as
well as horse roads, there has always been a strong opposition to the
use of the overhead trolley, and in some places, as, for instance, the
city of New York, this opposition has been so strong as to prevent the
introduction of the system until some other means of conveying the
current to the moving cars was devised. Many attempts have been made
to solve this problem, and the patents taken out on such devices can
be numbered by the hundred and possibly by the thousand. Inventors
in this field, however, have not met with all the encouragement they
could desire, owing to the fact that, notwithstanding opposition, the
overhead trolley has been permitted in all but about three or four of
the larger cities of this country, and the greater portion of those
of other countries. The principal well-founded objection that can be
raised against the trolley is that it is unsightly and destroys the
appearance of the street, but those who are opposed to it also claim
that it is dangerous, and that underground or surface systems would not
be. As a matter of fact it is not dangerous, and there is nothing on
record to show that it is. Many persons have been run over by trolley
cars, but this is no fault of the overhead trolley; it is due to the
fact that street railroads are permitted to run cars through crowded
streets at a speed that is too great for safety. Underground conduit
cars running at the same speed would run over just as many people. In
accusing the trolley of being dangerous it is sought to prove that
the current flowing in the wire can do harm; but the history of the
numerous roads in existence shows that, so far as human beings are
concerned, the trolley current is not fatal, although it can give a
decidedly unpleasant shock, such as one would not care to experience
the second time. There is just as great, if not greater, liability
of obtaining shocks from underground systems as from the trolley,
therefore the only real gain that can be made by their use is in the
artistic sense. From a financial point of view no underground system
so far devised can compare with the overhead trolley; but if any one
should devise anything hereafter that can be constructed at the same
expense and will not cost more for maintenance it will undoubtedly find
an extensive application. Until such a perfect solution of the problem
makes its appearance the field for these devices will be confined to
cities like New York and Washington, where the overhead trolley is not
permitted.
Every system of conductors that dispenses with the overhead wire is
called by the layman an underground trolley, but, properly speaking,
these systems may be divided into surface and subsurface conductors.
Both of these may again be divided into exposed and inclosed
conductors, and also into continuous and sectional conductors. Finally,
we may designate the various modifications as mechanical, electrical,
and magnetic, the mechanical being those that accomplish the result
by purely mechanical means, the electrical being those that employ
electrical devices, and the magnetic those that depend for their
action upon the attraction of magnets. The principal difficulties
that the inventors in this field have to contend with are the cost
of construction and the effective insulation of conductors. With the
overhead trolley the current flows out from the power house to the
cars through wires carried on poles, and the poles are themselves good
insulators; but to make the work doubly sure the conductors are secured
to glass insulators, which are practically perfect. The current returns
to the power house through the ground and the track rails. As it is
easier for the current to circulate in a short path than in a long
one, there is a continual tendency for it to jump from the overhead
wire through the insulation to the ground, but this is effectually
prevented by the very perfect character of the insulation. When the
outgoing and incoming wires are both placed upon or underground the
strain upon the insulation is very much increased, for then instead of
the two lines being separated by fifteen or twenty feet of pole, which
is a very fair insulator, they are separated by only a few inches of
earth or perhaps metal, the first of which is a fairly good conductor,
while the last is a nearly perfect one. It is evident, therefore, that
the insulation proper in an underground or surface system must be of
the highest order. If the conduits in which the wires are located
could be kept perfectly dry, there would be no difficulty in obtaining
insulation that would withstand the strain it is subjected to; but rain
in summer and snow in winter will at times cover the tracks and fill
the conduits, hence the securing of perfect insulation presents great
difficulties. The manner in which inventors have sought to surmount
the obstacles can be made clear by the aid of a few illustrations of
typical designs.
[Illustration: FIG. 25.--UNDERGROUND CONDUIT WITH PROTECTING SHIELD FOR
THE CONDUCTOR.]
Fig. 25 shows one of the forms of a class of underground conduits
belonging to the inclosed conductor type. The track rails are supported
upon the outer ends of large castings, _F F_, commonly called yokes.
These are made of such size that the portion below the opening which
incloses the conduit may be of sufficient depth to afford the requisite
strength to properly support the track. The conductor that carries the
current is located at _f_ and is insulated from the casing _j_, which
forms the lower half of the conduit, by the stands _g_. From the car a
bar, _P_, which is called a plow, projects downward through the slot
between the rails, _k k_, and on its end is spread out into a fork,
_d_, which carries a pulley, _e_. When this pulley is in contact with
the conductor _f_ the current passes through the plow _P_ to the motors
upon the car, and thence to the track rails and back to the power house.