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land, since these possess more interest for us than do the measures of
other nations, with which we are less familiar.

It is quite generally supposed that the length of a yard exactly cor-
responds to the length of a pendulum beating seconds of time, in a
vacuum, in the latitude of London, at the sea-level. This, however,
is not the fact. The act of Parliament in relation to this matter has
been generally misunderstood, for it does not declare the length of the
yard to be absolutely that of the pendulum ; in truth, these lengths
are not the same. Parliament only provided that, in ease the original
standard should be lost, it could be restored by reference; to the unit-
pendulum. The standard that was legalized was made by Bird, from
Graham's scale, in the year 17G0. It was named the "imperial stand-
ard yard."

According to experiments conducted at that time, it was found
that the relation between the length of the standard imperial yard
and that of a seconds-pendulum was in the proportion of thirty-six
inches to thirty-nine inches and ^'^Vi?o ^^ ^" inch. On October 16,
1834, both Houses of Parliament were destroyed by fire, and, although
the imperial yard was found in the ruins, it had become unfit for use
as a standard. The problem of its restoration was then presented, but
since the passage of the act of 1824, which declared the relations be-
tween the pendulum and the lost standard, it had been found that the
data from which the relations were calculated were, in several respects,
unreliable. It was finally decided not to attempt the restoration of
the lost standard by means of the pendulum, but to w^ork from the
various standards which had been compared with it. For this pur-
pose six different scales were found available, among which was
the tubular scale belonging to the Royal Astronomical Society ;
but this scale Avas not the principal authority from which the new
standard was constructed, although it is so asserted in both Apple-
tons' and Johnson's Cyclopjedias. The scales actually made use of
were two by Shuckburgh, one by Kater, that belonged to the Royal
Society, and two bars of the Ordnance Department. The work of
renewing the standard was intrusted to Sir Francis Baily, but he died



ABOUT MEASURES OF LENGTH. 655

before completing it, and was succeeded by the Rev. R. Sheepshanks.
That gentleman first constructed a bar of brass, which he found to
measure 3G'00025 inches, in terms of the lost standard. From this the
l)resent " imperial standard yard " known as " bronze 19 " was made.

Before Sir Francis Baily died, he proposed the use of an alloy for
standard measures, which is known as Daily's metal. It is composed
of sixteen parts of copper, two and a half parts of tin, and one part of
zinc. " Bronze 19 " was made of Baily's metal ; it is thirty-eight
inches long, one inch wide, and one inch d(;cp. The graduations are
upon gold plugs that are sunk into the bar. The lines are sharp, and
lire very well adapted to accurate measurement ; they are about yoVs"
of an inch in width. This standard was legalized by act of Parlia-
ment on July 30, 1855. The original standard "bronze 19," or, as it
is also called, " No. 1," is kept in the " Strong Room " of Old Palace
Yard. Four copies of it are in existence : one is at the Royal Mint, one
is in charge of the Royal Society, one is in the new Westminster
Palace, and the last is at Gi-eenwich Observatory. Forty other copies
were made in Baily's metal, and these have been distributed among
different Governments, but only two of them are standard at the same
temperature as the original.

From what has been stated, it will be observed that there is no
natural unit from which our yard-measure has been derived ; it is
merely an assumed unit of length which has been declared a legal
standard by the British Parliament.

The yard-measure of the United States, with which all measures to
be verified are now indirectly compared, is known as " bronze bar No.
11," which was presented to the Government by the British Board
of Trade in the year 1856. It is standard at 61-79° Fahr. It does
not appear, however, that our Congress has ever sanctioned the use of
this standard by any enactment. The only standard yard ever legal-
ized by that body seems to have been a copy of a part of an old scale
l>y Troughton, which had been used by the Treasury Department pre-
viously to 1856.

There is now a strong movement in favor of the general adoption
of the French system of weights and measures in this country. The
efforts that have been made to attain this very desirable result have
met with great opposition, but this is steadily giving way before ra-
tional argument and sound elementary instruction, so that we may
safely predict that our very irrational divisions of feet, inches, pounds,
and ounces will eventually be abolished, and that a decimal system
will take its place. There is a standard metre bar in the possession
of our Government, but it has not been declared a standard by Con-
uress, although it is used for comparisons.

The French metre was originally supposed to be equal to the one
ten-millionth part of the quadrant of a meridian of the earth passing
through Paris. An arc of a iiu'viJinii wliicii pvlcnds from Dunkifk to



656 THE POPULAR SCIENCE MONTHLY.

Barcelona, running through Paris, was very carefully measured by
Messrs. Mechain and Delambre, and, by comparing their results with
measurements that had been made of other arcs, they were able to ob-
tain the length of the meridional quadrant of Paris. Four iron bars
were then prepared, and their ends were ground and polished until
they were of the required length, to represent one ten-millionth part
of the quadrant, or one metre. One of these is now in the possession
of the United States, and it is supposed to be the only one in existence.
One of the original bars was chosen as the standard of France, and the
metre of the French Archives w^as made directly from it, and at the
same time two other similar bars were made, one of which is the metre
of the Conservatoire and the other is the metre of the Observatoire.
These bars are made of platinum.

In the year 1870 a Commission was formed at Paris, which is known
as the " Commission Internationale du Metre." This Commission, after
mature consideration, concluded that the natural unit which had been
assumed was far from satisfactory, for reasons which were well set
forth in the scientific journals at the time. The Commission therefore
declared, as it had full power to do, owing to its international charac-
ter, that the metre of the Archives should be perpetuated for ever as
the true metre. It thus appears that the French unit is no more firmly
established, so far as any natural basis is concerned, than is the English
yard. It may be of interest to know what relation the accepted stand-
ard bears to the length of the natural unit that was first proposed.
It has been shown, by the more recent investigations of Clark and Shu-
bert, that the Archives-metre falls short of being true to the natural
unit by one fifty-four-hundredth part.

The iridio-platinum alloy, which the Commission has decided to
use for standards, is " composed of ninety parts of platinum and ten
parts of iridium, with an allowance of two per cent, variation more or
less." In 1874 an '• International Bureau of Weights and Measures "
was established at Paris, to be supported by^^ro rata contributions from
the signing powers. This bureau is charged with the care of proto-
type standards, and with the duty of constructing and verifying
copies of them.

The work of preparing the prototypes devolved upon the French
section of the Commission, but the International Bureau declined to
accept the standards that were submitted, on the ground that the
platinum-iridium alloy contained about two per cent, of iron, and was
not, therefore, of sufficient purity. The work of the Bureau has been
delayed on account of this unfortunate circumstance ; but M. Tresca,
the secretary of the French section, does not admit the validity of the
objections that have been made to the alloy. The buildings of the
International Bureau afford great facilities for its work ; in one room,
where standards of w'eight are compared, there is a very perfect appa-
ratus for weighing in a vacuum. It is so arranged that the weigh-



ABOUT MEASURES OF LENGTH. 657

ing can be done from a distance of about eight metres (over twenty-
five feet) from the balance. In the room where standards of length
are compared, there is a comparator which cost about three thousand
dollars, and another one is probably completed by this time, which is
worth five thousand six hundred dollars.

It seems strange that the precise relation existing between the
imperial standard yard and the metre of the Archives is not known.
Nevertheless, it is true, for the two measures have never been directly
compared. No equation can be assigned to them that is not likely to
be erroneous by at least "005 of an inch ; but, in the year 1878, Par-
liament declared that the legal value of the metre, in inches, should be
39 -37076.

It may be thought that so small an error as five one-thousandths of
an inch, in a bar more than three feet long, is not worthy of serious
consideration ; but the fact is, that any error that can be detected by
the most refined instrumental means is of great consequence, espe-
cially for scientific work. The error mentioned above will appear
as a relatively large one, when we state with what accuracy minute
measurements may be conducted. Professor Rogers considers that
the error in comparing the length of two metre bars need not ex-
ceed the one-millionth part of a metre. In terms of an inch this error,
expressed in figures, would be -0000039. In testing the performance
of his excellent comparator, he found the value of a centimetre, in
terms of an inch, to be -393707. The generally accepted value is
-393708, which indicates a truly wonderful degree of accuracy in the
instrument.

Professor E. W. Morley has made some experiments to determine
the probable error in microraetric measurements, and he has found
that the errors of a single observer, under the particular conditions
described, were very small. With a low-power object-glass, the prob-
able error does not exceed thirty-nine ten-millionths of an inch. With
a greater magnifying power he found it to be about thirty millionths
of an inch. These errors, inconceivably small as they are, can be
made appreciable by means of a microscope.



ARE CEMETERIES UNHEALTHY?

Bv M. G. ROBINET.

IF the tomb is characteristic of humanity, as Vico has said, the cem-
etery, M. Pierre Lafitte remarks, is absolutely necessary to all
human society. It not only furnishes a more or less hygienic method
of disposing of the bodies of those who are no more — it is also a fun-
damental institution, in the sense that it is a symbol in no way arbi-

TOL. XIX. — 42



658 THE POPULAR SCIENCE MONTHLY.

trary of human continuity. The cemetery ought, therefore, in every
city to be preserved and improved, as something indispensable to the
intellectual and moral improvement of the people. It constitutes an
interest of the first order, the care of which justifies all necessary
efforts and expenditures. With a large part of the public, however,
hygienic considerations far outweigh all the moral and social advan-
tages to be derived from the maintenance of cemeteries ; and, in justice
to the views of this class, it is proper to inquire to what extent the ex-
istence of cemeteries, in or near a city like Paris, can be dangerous to
the public health.

The injurious effects attributable to cemeteries can be exhibited
only through the air, the soil, and the waters. Let us examine each
of the three cases.

The air may be contaminated by the disengagement of jjoisonous
gases, or by the propagation of miasms.

The decomposition of bodies in the earth is a real organic com-
bination ; its products are quite well known. The principal and most
abundant of them is carbonic acid, a substance that is generated by
the slow combustion of the carbon contained in all organic matter,
vegetable or animal, whether it be a blade of grass, a leaf, wood, ma-
nure, or a dead body. It may be disengaged from the soil in ceme-
teries, and most hygienists have till now considered it one of the prin-
cipal causes of their insalubrity. This is a mistake. We have on a
recent special occasion made an approximate calculation of the maxi-
mum quantity of carbonic acid that can be produced in the cemeteries
of Paris. The results of these calculations, which are based upon nu-
merous weighings of corpses made in several hospitals and on the most
authentic data of the chemical composition of the human bod}', show
that this quantity is infinitely less considerable than has been supposed.
The total weight of the bodies consigned each year to the cemeteries in
Paris is 1,389,000 kilogrammes (3,472,500 pounds). If all their carbon
were transformed (which is not the case) and disengaged as carbonic-acid
gas, they would furnish 1,257,000 kilogrammes (3,142,500 pounds) of
that gas in five years. Now, according to the calculations of M, Bous-
singault, we may estimate the quantity of carbonic acid produced in
Paris, by the respiration of men and animals and the different processes
of combustion, at 18,000,000 kilogrammes (or 45,000,000 pounds) in
twenty-four hours. The combustion of illuminating gas alone in Paris
(21*5,813,875 cubic metres) produced last year a quantity of carbonic
acid thirty-five hundred times more considerable than all the dead
buried in the cemeteries during five years could give at the maximum
rate of exhalation. The Grand Opera-IIouse alone gives out every
year thirteen times more carbonic acid from its gaslights than could
be disengaged from all the cemeteries put together, even if all their
carbon were converted into gas.

After examining these figures, and comparing them with the very



ARE CEMETERIES UNHEALTHY ? 659

precise experiments recently made by MM. Jules Reiset, Muntz, and
Aubin, on the proportion of carbonic acid in the atmosphere, which
go to show that the proportion of this gas in the air of Paris is no
more considerable than in the country, we have a right to affirm that
positively no danger to the public health exists from this source.

The truth is, that most of the accidents which happen in burial-
places must be attributed only to confined carbonic acid. These acci-
dents are, moreover, much less numerous than is supposed. Different
authors do not report more than twelve or fifteen cases, and the theory
that cemeteries are centers of infection has been built upon this small
basis. Such accidents have been attributed to " pestilential emanations,
to certain subtile and deleterious gases, to unhealthy miasms," etc. In
reality, the accidents noted have been caused by the carbonic acid
which has settled in the pits or vaults by virtue of its superior specific
gravity. The same happens much more frequently than in cemeteries,
in lime-kilns, marl -pits, some cellars, fermenting vats, everywhere,
in short, that carbonic acid is liable to accumulate within a limited
space.

The absence of any facts relative to other gases than carbonic acid
that might be disengaged in the course of cadaverous decomposition
ought to have made those who are so sure of the dangerous character
of cemeteries more circumspect ; notwithstanding there are no such
facts, these persons, besides magnifying the dangerous consequences
of the liberation of carbonic acid, speak also of the no less fearful
dangers which result from the generation of " certain gas^s and of
certain volatile products." Only two gases have been found to be
present to an appreciable extent in the confined air of mortuary vaults,
or in the atmosphere immediately surrounding a body in decompo-
sition — as, for instance, Avithin the inclosure of a leaden coffin. These
two gases are poisonous when breathed in a certain quantity ; they
are ammonia and sulphuretted hydrogen, forming, when they combine,
sulphohydrate of ammonia. The most delicate reagents disclose no
trace of these gases in the free air, nor even in the atmosphere of the
cemeteries of Paris, although such tests often, when applied in the
same manner, indicate their presence in water-closets, sinks, cellars,
and sewers. In the absence of ammonia and sulphuretted hydrogen,
we might (though no one has yet done so) imagine the presence of the
jHoma'ines, those alkaloids of dead bodies recently discovered by Pro-
fessor Selmi. "We anticipate this accusation, by observing that the
presence of ptomaines in the open air has never been detected. It has
been proved that they are not always poisonous ; and they exist only
in inconsiderable quantities. So far as is known, the ptomaines may
be simply resultants of the transformation of other principles during
extraction, for " they sometimes exhale a perfume like that of certain
flowers, as the orange or wild-rose, and of certain aromas " — odors
which it is well known are not found among those of cadaverous pu-



66o THE POPULAR SCIEXCE MOXTHLY.

trefaction. Moreover, these alkaloids, according to Selmi, are readily
decomposed in contact with the air. The ptomaines, then, can not
enter into account in establishing a noxious character for cemeteries.

Assuredly there are miasms. We do not mean by this terra those
famous entities by which populations have been struck wdth terror,
but those infinitely small, inferior organisms, the microbes, whose ex-
istence can not be disputed after the brilliant investigations of eon-
temporary micrographs, especially those of M. Pasteur. We have no
disposition to ignore the existence of four or five species of microbes,
the destructive effects of which appear to be well established, such as
the anthrax- bacteria, the septic vibrion, Obermeyer's spirill, the micro-
coccus of the hen-cholera, and some other less well-known bacteria.
But, without denying that the air may convey infectious germs, and
that these may penetrate into the human organism through various
channels of absorjDtion, facts which have become almost classical, we
still have to examine whether cemeteries, more than other places, give
rise to these miasms, these legions of microbes, whose presence in con-
siderable numbers in certain places, notably in hospital-wards, is in-
contestable.

A number of well-established facts go to prove that the different
germs are destroyed by the combustion of corpses in the earth as soon
as putrid fermentation begins. We cite the characteristic fact of the
disappearance of the earbuncular virus in the bodies of animals that
have died of the plague-sore, from the moment the body begins to
putrefy (Pasteur, Collin), a fact which is practically recognized by all
the horse-killers, who are aware that infected subjects shortly after
death cease to be dangerous to them. A more important fact is that
the very exact micrographic researches undertaken by M. Miquel in the
cemeteries of Paris have certainly shown that there do not exist in
them any centers specially productive of genns of cryptogams. This
learned physician has ascertained, contrary to the opinion of many
authors, that the vapor of water which arises from the soil, from riv-
ers, and from masses in active putrefaction, is always micrographically
pure — that is, it contains no microbes ; that the gases proceeding
from buried matters in decomposition are always free from bacteria ;
that even the impure air which is caused to pass over putrefied meats,
instead of being charged with microbes, becomes fully purified, on the
single condition that the infectious and putrid filter is in a condition
of humidity comparable to that of the ground at about a foot below
the surface. Finally, none of the numerous species which M. Miquel
has isolated and inoculated upon living animals has shown itself ca-
pable of determining pathological troubles worth mentioning. After
this, we may with perfect security put aside those pretended miasmatic
emanations, those mysterious eflluvia with which certain hygienists
have gratuitously frightened an inexperienced public, and which some
speculators have turned to good account for themselves.



ARE CEMETERIES UNHEALTHY ? 661

Regarding the extent to which the soil is affected in consequence
of burials, we are in possession of exact and well-established facts.
The time required for the earth fully to transform organic matter that
may be buried in it varies according to the physical and chemical nat-
ure of the soil : in some grounds bodies are, we might say, devoured
in a few days ; more commonly the time required to transform a corpse
is estimated at from five years, as in Paris, to twenty years, as at Geneva,
and even more in some places. Authors also differ respecting the time
needed for the operation : Gmelin and Wildberg believed that it takes
thirty years, while Maret thought that three years are enough.

Legislation based on this point has designated a variety of periods
after which burial-grounds may be used over again. At Frankfort, thirty
years is the standard ; at LeijDsic, fifteen years ; at Milan and Stuttgart,
ten years ; at Munich, nine years. Generally, the time necessary for a
complete destruction of the body is estimated in France at five years,
but this limitation is not at all absolute, and in many cases burial-
grounds may be used anew before that time. In the majority of the
experiments made by them, Orfila and Lesueur found that bodies were
reduced to skeletons at the end of fourteen, fifteen, or eighteen months.
After that time, the soil under the vivifying influence of oxygen re-
sumed its original qualities.

On this point, we may assert, contrary to certain affirmations, but
in accordance with experiments the importance and value of which are
guaranteed by the name of the author, M. Schutzenberger, that, so far
as the cemeteries of Paris are concerned, no saturation of the soil,
either with gases or with solids, exists. The recent experiments of
this chemist have resulted, in effect, in showing that the soil in the
Parisian cemeteries is still in a sufficiently favoi-able condition as to its
composition to effect the absorption of the gases and the complete
transformation of the solid and liquid matters resulting from the pu-
trefaction of the bodies that may be buried in them. The analysis, so
far as it refers to gases at least, has given identical results with the
analyses of good arable lands. Moreover, there is nothing to prevent
the modification of the soil of cemeteries by means of suitable appli-
cations for augmenting the intensity and rapidity of its combustible
force. Such applications are certainly not beyond the means of modern
agricultural chemistry.

No important instance of the contamination of waters has been es-
tablished against the cemeteries. Cases of an excej)tionally unfavor-
able influence of a mass of decomposing matter on certain waters may
occasionally occur, but none such have been established in the soils of
Paris, and those which have been described in other places are not
conclusive. What, on the contrary, most evidently comes out after a
study of the facts is the remarkable purifying power that the earth
possesses. It would take too long to give here the proof that water
is not infected by cemeteries ; we mention only the case of the well in



662 THE POPULAR SCIENCE MONTHLY.

the cemetery of Montparnasse, the water of which is shown by chemical
analysis to be of excellent quality.

With respect to the inferior organisms which some persons believe
may be conveyed away by water that has traversed the soil of cem-
eteries, we may say that M. Pasteur has showm that the waters of
springs issuing from the ground even at a slight depth, are so desti-
tute of germs that they can not fertilize the liquids which are most
susceptible of change. Such waters, says M. Pasteur, " are at the base
of lands which have been traversed incessantly for centuries by streams,
the effect of which has been constantly to cause the finest particles of
the superposed soils to descend to the springs. The latter, in spite of
these favorable conditions for polluting them, remain indefinitely of a
perfect purity, a manifest proof that a certain thickness of earth arrests
all the finest solid particles."

The wells in Paris being hardly ever used, they ought to be infected
by the nitrates which, supposed to be introduced into them, are not
drawn from them. It is, however, far from being proved that the



Online LibraryD. S. (David Samuel) MargoliouthThe Popular science monthly (Volume 19) → online text (page 82 of 110)