_To the Editor of the Scientific American:_
I write to relate an incident which may be of interest to some of the
readers of your valuable paper. There is a bar iron mill, situated
in a neighboring town four miles from here, that has been on fire
three or four times, in which the English sparrow might be called the
incendiary. These sparrows pick up old pieces of cotton waste, which
they build in their nests, among the timbers of the roof of the mill,
and in every case of the fires above mentioned, these nests were the
cause, either from spontaneous combustion or from sparks from the hot
iron striking and lodging in the nest. If you could suggest some way of
getting rid of the sparrows, I think the manager of the mill would be
glad to adopt your plan.
R. W. KEAR.
Pottsville, Pa., February 14, 1887.
Charcoal as Fossil.
_To the Editor of the Scientific American:_
Perhaps charcoal has not often been observed as occurring naturally
with mineral coal, though, as a result of metamorphism, graphite is not
uncommon in coal districts.
In a variety of bituminous coal that comes from Tennessee, and that is
largely used in this State, there are to be seen along in the cleavage
planes films of true charcoal, in varying quantity, but commonly thin.
This coal has been coming to us for several years, and all the while I
have noticed in it the presence of the charcoal. I have scarcely ever
put coal into the fire without making the observation; and there is
perhaps not a lump, of size at all considerable, that does not contain
these films.
On close examination, I have frequently found that the surface of
the films on the broken lumps contains a delicate tracery, closely
resembling vegetable impressions. The tracery is not so well marked as
a fossil imprint, but not so indistinct as to escape notice.
J. F. B.
Emory College, Ga.
Phosphorescent Birds.
_To the Editor of the Scientific American:_
In reading of the habits of the wading birds, and particularly of the
crane, I do not find that naturalists give any account of their manner
of attracting their prey at night. My attention was called to the
matter while gigging for fish, by frequently observing dim phosphoric
lights appear and disappear along the shore like jack o' lanterns,
which I for a long time supposed them to be. Oh one occasion I fired
at such a light, and brought down a large blue crane, on which the
phosphoric spots were clearly visible after death. There are two such
spots; the larger being high up on the breast and the smaller at the
bottom of the breast bone, the bird having power to reveal and conceal
them at will. I have since stuffed many of the water walkers, and find
that all have the same general arrangement of the feathers, and, as I
believe, the same power of lighting up the water to attract the fish.
Will some naturalist who is posted on this subject please throw some
further light upon it, for the benefit of science?
ISAAC N. WORRALL.
Topeka, Kansas.
Canned Fish, Meats, etc.
A correspondent in British Columbia, who is engaged in the business,
gives us the following practical information:
Noticing your reply to a correspondent anent canned goods, I recently
opened several cans of salmon that were processed in July of 1879,
1880, 1881, and on comparing them with last season's cans, found it
impossible to detect the slightest difference. I hold that if a can is
once perfectly sealed, the contents will remain unaltered as long as
the metal casing remains intact.
A can will keep if every portion of the contents has been subjected to
a temperature of 212° Fah., whether the air is expelled or not, as my
experiments have conclusively proved.
When I first began the business, I was taught that the air unless
expelled would cause the contents to deteriorate, and that was the
reason the cans were vented. I soon found it was a mistake. The venting
is done for the purpose of testing for leaks. A tight can has a sound
that cannot be mistaken for a leaky one. If your correspondent boils
his fish, flesh, or fowl with the vents open, he will have dry cans
for his pains. The vents must be closed when cooking, and opened, in
the case of meats, after boiling one hour, then closed and returned to
kettle, and boil three hours for fish and less for meat without bone.
Fruit is vented and closed when finished.
S. H.
OUR WINTER BIRDS.
BY E. M. HASBROUCK.
It is a popular belief that the woods and fields in winter time are
void of bird life, and are what they appear at a distance--a cold,
bleak, and desolate waste.
This opinion, however, is not correct. It is true that the birds, which
were so numerous during the summer, have left us and gone to their
winter homes, but as they departed an entirely different fauna started
from a colder climate, and gradually took their place. I refer to the
birds of the northern part of Canada and the fur countries, whose
summer homes are in these desolate regions, and which on the approach
of winter are driven southward, making a temporary stay with us until
the rigors of an Arctic winter shall have departed, and once more left
their homes in an inhabitable condition.
[Illustration]
A glance at these birds will take one into the same localities that
have been so often traversed in the summer time, and once within
the woods, the fact that they are cold and leafless is lost sight
of. One can now find birds entirely different from any that he has
heretofore seen, and at the same time learn several facts of interest
concerning birds with which he considers himself well acquainted; as,
for instance, the American goldfinch, which is supposed to migrate in
the fall, will be found in the swampy woods in large flocks, but with
plumage so changed that they will probably not be recognized, being
of a somber brown color, and sexes undistinguishable. Why hundreds of
a species, the majority of which migrate regularly, and which do not
reach us until late in the spring, should change their dress and remain
with us throughout our most severe winters is a problem.
In company with them will often be found the pine linnet and common
red poll. These little finches are rather rare, and are seldom found
together in any great numbers. They leave the North in large flocks,
but as they journey southward break up into smaller and smaller
companies, until only a few are left together. These join interests
with the nearest goldfinches, and remain with them throughout the
winter.
The results of a visit to the fields, on some clear day, will often
repay a somewhat wearisome tramp. The snow buntings and shore larks
frequent such places in large numbers, and a locality where the ground
has been swept bare of snow, or is covered with a growth of weeds, is a
favorite feeding ground.
Their food consists entirely of the seeds, and a spot once chosen by
them is seldom forsaken until all in this line has been eaten.
The buntings will be found in flocks of from a dozen to two hundred,
and in some even more. Their appearance when flying is pure white, but
the upper parts of a specimen in the hand will be found mostly black.
They are extremely shy, and when approached spring into the air and
dart away in a manner that would indicate their intention of departing
for the next county; but should you return that way in the course of
half an hour, you will, in all probability, find them in the same place.
The shore larks, although feeding on the same grounds, seldom mix with
the buntings, preferring to keep in flocks by themselves, and are
worthy of attention, inasmuch as they have one marked peculiarity; this
is the small tuft of feathers on each side of the head, resembling
minute horns, which are raised and lowered at pleasure. (See cut.)
The majority of these birds reach us at the approach of cold weather,
although a few spend the summer here and rear their young. They are
less timid than the snow bunting, and may often be approached quite
close.
These two species form about all the attraction to be found to any
extent in the fields, and, aside from an occasional hawk, only one more
species frequents them, a species that is worth going miles to see--the
snowy owl.
These birds reach us about the last of November and remain until the
last of February, frequenting the neighborhood of some body of water,
and seldom straying from it more than a mile or two. To see them and
become at all acquainted with their habits, one must face all kinds
of weather, possess untiring energy, and must undergo a considerable
amount of fatigue. He will find them in the open country (as they
frequent such ground altogether, seldom, if ever, entering the woods),
perched on some fence post or stump, where, if undisturbed, they will
remain for a considerable length of time, intently watching for mice,
of which their food largely consists, set off by an occasional rabbit.
They are extremely rare. One may tramp the fields for several days
without success, and then again find one the first hour out.
On December 20, 1886, the writer started on a trip to Oneida Lake, N.
Y., intending to devote his attention entirely to these birds; was gone
four days, and saw five birds. This, of course, was exceptional, but
shows what may happen.
In the dense pine and hemlock swamps several other species of owls are
found, which are much more numerous at this season than in the summer.
These are the long eared and short eared owls, with an occasional
barred owl; but the most interesting of all is the Acadian or saw-whet,
one of the smallest of the family and little known. It is far from
common, being met with only at intervals. Its note, which closely
resembles the filing of a large saw, occasionally betrays it; while at
the same time it has a tendency to stray into barns and out-buildings,
thus affording an opportunity for capture.
As it is not generally known, a description may be of some benefit.
"Upper parts, including wings and tail, uniform chocolate-brown,
spotted with white; under parts white, thickly streaked lengthwise with
the color of the back; face, white."
In general appearance, they are the same as all owls, but when seen in
the woods have a somewhat comical appearance, owing to their wise look
for so small a bird.
We have often heard of the shrikes, or butcher birds, that capture
small birds and impale them on the thorns of bushes. Many of us have
wished to see them, and wondered where and when they were to be found.
Now is the time. Any clump of bushes or young second-growth is a likely
place to find them, for there are two species which visit us every
winter and frequent these places. These are the great northern and
loggerhead shrikes, the latter being most common; both bear a general
resemblance, but differ mainly in size and in markings on the under
parts. One can find them almost any day, perched on the topmost branch
of some tree or bush, steadily eyeing the surrounding bushes in search
of some victim, while on a thornbush near by will be found numberless
moles, mice, and an occasional bird, awaiting the appetite of the
marauder.
Aside from the goldfinches, many other birds of different species,
instead of migrating with the rest, remain behind, and are to be found,
on almost any pleasant day, in the warmer and more secluded parts of
the swamp. Among these are the robin, golden-winged, downy, and hairy
woodpeckers, the white-bellied nuthatch, and chickadees. These last
are, perhaps, the most numerous of all our winter birds; whole flocks
roam from one end of the swamp to the other, and I think there is no
pleasanter sound to be heard in the woods in winter than to hear their
clear "chick-a-dee-de-de-de" from a score of little throats, or to see
them clinging to the branches and acting as familiarly as though no one
was within sight or hearing. An occasional meadow lark will be flushed
from the tall grass in some sheltered spot, while on the open streams
will be found black ducks and mallards, whistlers and mergansers of two
species, the hooded and buff-breasted or common sheldrake.
Truly, then, with all this material awaiting us, the fields and forests
will be found inviting, and you who have never traversed them in winter
do so now, and get a new interest awakened in them.
* * * * *
IT is not long since we spoke of the benefits conferred on the farmer
by the inventor. The following statement is a good illustration of our
views as then presented. It is taken from our contemporary, the _New
England Farmer_. "By the use of mowing machines and horse rakes and a
horse hay fork, two boys in Connecticut last summer cut, raked, and
helped to stow away 100 tons of hay, while their father was disabled
from work by illness. Under such conditions a farmer is apt to feel
like blessing the man who invents labor-saving machinery."
THERMOSCOPIC BALANCE.
BY GEO. M. HOPKINS.
The action of this instrument is due to the facility with which liquids
evaporate in a vacuum. A small amount of heat is sufficient to vaporize
the liquid to the extent required to secure the desired action. The
instrument is provided with a glass tube bent twice at right angles,
and having a bulb blown on each end. The tube and the bulbs are partly
filled with water, and a vacuum is secured by boiling the water in the
bulbs before sealing them. The center of the tube is furnished with
V-pivots, which rest in bearings in the top of the forked column. The
column also supports a metal screen, which is bright one side and black
on the other. Two pins project from the shield, to limit the movements
of the glass tube and bulbs.
When the instrument is in use, the screen is placed toward the source
of heat, and when radiant heat strikes the bulb which is unshielded
by the screen, the water in that bulb is vaporized, and sufficient
pressure is produced to drive the water upward into the bulb behind
the screen. When a little more than half of the water has been in
this manner forced from the lower to the higher bulb, the upper bulb
preponderates. The tube and bulbs are supported on their pivot so as
to secure unstable equilibrium, so that, when the upper bulb begins to
descend, it completes its excursion at once, and exposes the full bulb
to the radiant heat, at the same time carrying its empty bulb behind
the screen, where it cools. The transfer of the water from the full
bulb to the empty one now occurs as before. This operation is repeated
so long as the bulbs are exposed to the action of radiant heat. The
oscillations may be quickened by smoking the sides of the bulbs remote
from the screen, and still greater rapidity of action may be secured
by concentrating the heat on the bulbs by means of condensers or
reflectors.
[Illustration: THERMOSCOPIC BALANCE.]
The Duration of the Sun.
The _Builders' Weekly Reporter_ (London) has an interesting account
of a lecture at the Royal Institute, given by Professor Sir William
Thomson, on the latest dynamical theories regarding the "probable
origin, total amount, and possible duration of the sun's heat." During
the short 3,000 years or more of which man possesses historic records
there was, the learned physicist showed, no trace of variation in solar
energy; and there was no distinct evidence of it even though the earth,
as a whole, from being nearer the sun, received in January 6½ per cent
more heat than in July. But in the millions of years which geology
carried us back, it might safely be said there must have been great
changes. How had the solar fires been maintained during those ages? The
scientific answer to this question was the theory of Helmholtz that the
sun was a vast globe gradually cooling, but as it cooled, shrinking,
and that the shrinkage--which was the effect of gravity upon its
mass--kept up its temperature. The total of the sun's heat was equal to
that which would be required to keep up 476,000 millions of millions
of millions horse power, or about 78,000 horse power for every square
meter--a little more than a square yard--and yet the modern dynamical
theory of heat shows that the sun's mass would require only to fall in
or contract thirty-five meters per annum to keep up that tremendous
energy. At this rate, the solar radius in 2,000 years' time would be
about one hundredth per cent less than at present. A time would come
when the temperature would fall, and it was thus inconceivable that
the sun would continue to emit heat sufficient to sustain existing
life on the globe for more than 10,000,000 years. Applying the same
principles retrospectively, they could not suppose that the sun had
existed for more than twenty million years, no matter what might have
been its origin--whether it came into existence from the clash of
worlds pre-existing, or of diffused nebulous matter. There was a great
clinging by geologists and biologists to vastly longer periods, but the
physicist, treating it as a dynamic question with calculable elements,
could come to no other conclusion materially different from what he had
stated. Sir William Thomson declined to discuss any chemical source
of heat, which, whatever its effect when primeval elements first came
into contact, was absolutely insignificant compared with the effects of
gravity after globes like the sun and the earth had been formed. In all
these speculations they were in the end driven to the ultimate elements
of matter, to the question--when they thought what became of all the
sun's heat--what is the luminiferous ether that fills space, and to
that most wonderful form of force upon which Faraday spent so much of
the thought of his later years--gravity. The lecture was heard with
deep interest and close attention.
IMPROVED MARINE DREDGER.
The twin screw dredger Dolphin was recently constructed for the
Colonies, under the direction of Sir John Coode, assisted by Mr. Wm.
Matthews, C.E., and is especially designed, says the _Engineer_, for
harbor improvements in the West Indies. The dimensions are:
Ft. In.
Length between perpendiculars 130 0
Breadth moulded 30 0
Depth 8 0
ENGINES--Compound surface condensing, I.H.P 250
Stroke of pumps 14
Diameter of high pressure cylinder 16½
" low pressure " 33
Length of stroke 24
Diameter of air pump 11½
" circulating pump 6½
" feed pumps 2½
" bilge pumps 2½
The boiler is of steel, for a working pressure of 90 lb. per square
inch. The bucket ladder works through a well formed in the center of
the vessel, and dredges to a depth of 33 ft. below the water level,
and the buckets are made wholly of steel, and are capable of lifting
250 tons of free soil per hour. Triple-geared winches are supplied at
bow and stern for working the mooring chains, the barrels of which can
be worked independently or conjointly, as required. The cabins for the
officers and crew are of the most complete description; those of the
former being fitted on starboard side of the well, and consist of rooms
for the captain, mate, and engineers, also mess room. All the rooms
are large and efficiently lighted and ventilated. A powerful crane is
erected at forward end for overhauling the buckets, hoisting gear, etc.
[Illustration: THE DREDGER DOLPHIN.]
Hydraulic Dredging at Washington.
At a recent meeting of the Engineers' Club of Philadelphia, a paper by
Conway B. Hunt was read on hydraulic dredging machinery.
The paper mentions the early application of the principle of hydraulic
dredging, that is, the mixing of dredged material with water and then
removing the mixture by suction or otherwise; and after referring
briefly to the Roy Stone and Bowers dredges as typical machines,
describes in detail the Von Schmidt dredge. Two of these dredges are
engaged on the improvement of the Potomac River at Washington, D. C.,
under the United States Government. Each is 100 feet by 50 feet, with
a semicircular bow, around which travels a vertical suction pipe, 22
in. in diameter, and telescopic. At its foot is a conical hood, beneath
which works a rotary excavating plow, 8 feet in diameter. The suction
is produced by a powerful centrifugal pump, run by a 200 horse power
engine.
The discharge pipe is 20 in. in diameter, has rubber hose joint
connections, and is carried to the shore on pontoons. The material was
mixed with from three to ten times its volume of water, and discharged
at distances up to 3,500 feet from the dredge, and at from 6 to 10 feet
above water. A year's record shows an average of 175 cubic yards per
working hour, and 2,300 yards per day, for each dredge. The work was
done, by contract, at prices of 12.37 cts., 15 cts., and 15.45 cts. per
cubic yard, which includes the cost of levees to confine the semi fluid
material, drains to carry off the water, etc. The final estimates were
specified to be taken by cross sections of the completed fill after
it had become solidified and compacted. In conclusion, it is noted
that the devices and details of hydraulic dredging machines are the
subjects of numerous patents, and their most efficient combination may
be long deferred. The large number of machines that are still in the
experimental stage of development would indicate that the best results
attainable from this class of dredges have not yet been accomplished.
A New Sugar Process.
The details of the process vary with quality of beets. To a vat
containing the secondary products to be treated are added calculated
quantities of diluted hydrochloric acid and milk of lime at 25° B. The
mass is heated to the boiling point by a steam coil. In a separate vat
the product is diluted with water at 75° C. to 23° B., and subsequently
run through Puvrez filtering bags. The filtrate is clear in color,
and is received in a measuring tank, from which it is run into the
diffusion battery. In the latter but few changes are necessary. It is
said that by this method an additional 1 per cent sugar is extracted
from the beet, and the white sugar obtained can be at once placed upon
the market.
* * * * *
THERE were exported last season from Prince Edward Island
91,000 cases of lobsters.
THE NORTHERN LIGHTS.
When, in 1752, Franklin succeeded, through a kite sent up into a storm
cloud, in obtaining an electric spark at the extremity of the cord,
which had been made a conductor through the rain, it was no longer
possible to doubt that lightning was but an immense electric discharge
between two clouds, or a discharge between a cloud and the earth. This
discovery was of great importance, since it connected with the laws of
physics certain phenomena which, until then, had passed for marvelous,
and in which nothing but supernatural and mysterious manifestations
were seen.
The aurora borealis, which is more difficult to understand, and which
necessitates more extended scientific notions, has remained much
longer unexplained. This enigmatic phenomenon was especially striking
to the imagination of ancient peoples. It was regarded as an omen of
inauspicious events, and the historians who describe it affirm that, at
times, armies have been seen passing through the bloody heavens, and
that the clash of arms has been heard.
It is now known that the aurora borealis has the same origin as
lightning, that it is one of the visible manifestations of atmospheric
electricity, and that it is due to slow movements of that fluid, while
lightning is the result of violent motions. The effects of the aurora
and of the thunderbolt are absolutely different; but between them there
is an intermediary that connects them, and this is heat lightning.
These elementary notions are now the property of science; but the study
of the aurora has hitherto been only partially outlined. Travelers
and physicists have, indeed, given numerous descriptions, but it has
remained to find the bonds that unite these so important phenomena
in the economy of the globe, to study the causes that set them in
action, to observe the correlations that they may offer, and to discuss
theories. This is a labor that Mr. S. Lemstrom has been engaged in for
several years, and we now propose to analyze the results published by
this great Finnish physicist.