This group is of fresh and brackish-water origin, and very variable in mineral character and thickness.
It rings when struck with the hammer, whence its name; is compact, and usually of a greyish blue or brownish colour; is variable in composition, but almost entirely composed of feldspar.
But many lodes in Cornwall and elsewhere are extremely variable in size, being one or two inches in one part, and then eight or ten feet in another, at the distance of a few fathoms, and then again narrowing as before.
Such clay-slates, in fact, are variable in composition, and sometimes alternate with fossiliferous strata, so that they may be said to belong almost equally to the sedimentary and metamorphic order of rocks.
I have for example in a given problem two variable quantities x and y, of which one cannot vary without causing the other to vary also under fixed conditions.
As is the relation of the mathematics of variable magnitudes to that of invariable quantities, so is the relation of the dialectic method of thought to the metaphysical.
They are almost as fantastic and variable as the forms of the kaleidoscope, although, as a general rule, they lack the symmetrical arrangements and proportions of that scientific toy.
And this is especially true of that vast and fathomless star-stratum, called the Milky-way, in which most of these peculiar phenomena occur, with the exception of the variable stars only.
Also, owing to the dichroism of the ruby the red is variable according to the changing position of the stone.
Commercial acetophenone contains variable quantities of impurities which reduce the yield.
Intelligence itself can scarcely be morevariable .
The apparent size of it will also be variable according to its supposed distance.
Remember, good Mr. Lieutenant, that God who with his finger turneth the unstable wheel of this variable world, can in the revolution of a few days bring you to be a prisoner also, and to be kept in the same place where now you keep others.
But the zoologist will inform him that species of animals are onlyvariable within certain limits, and are not transmutable, in so far as experience and experiment are concerned.
It is therefore necessary, when driving a vehicle with a petrol engine, to arrange some forms of variable speed-reducing transmission gear between the engine and the driving axle.
In many measurements what is sought is not the value of a single quantity, but the relation between the values of two variable quantities.
A solution of an equation which contains more than one variable is a set of values of the variables making the equation true.
I notice that it throws up its column of water with variable force: sometimes sending it to a great height, then again to a lower, which I attribute to the variable pressure of the steam accumulated in its reservoir.
The vault that spanned the space above, the sky, if it could be called so, seemed composed of vast plains of cloud, shifting and variable vapours, which by their condensation must at certain times fall in torrents of rain.
The variable factor is, not the law, but our own volition; and it is by combining this variable factor with the invariable one that we can produce the various results we desire.
At the time of the variable new year, the lamas and nuns retire to the monasteries, and dulness reigns in the valleys.
These are deep, fierce, variable streams, which have buried the lower levels under great stretches of shingle, patched with jungles of hippophae and tamarisk, affording cover for innumerable wolves.
Will the Meteoric Theory account for the Phenomena of Variable and Temporary Stars?
Such meteoric rings of varying density, like those revolving about the sun, would evidently produce the phenomena of variable stars.
It has been found, moreover, that the light of variable stars does not increase and diminish symmetrically on each side of the maximum, nor are the successive intervals between the maxima exactly equal to each other.
Will the meteoric theory explain the phenomena of variable and temporary stars?
It has been remarked respecting variable stars, that in passing through their successive phases, they are subject to sensible irregularities, which have not hitherto been reduced to fixed laws.
Owing to variable winds, we could not reach Dartmouth before the 14th of October; and having continued there till the 20th of that month, we warpt out of the harbour, and set sail to the S.
Then a precipitous hill blocked the way, extending a considerable distance along the creek, and leading sheer to the water from a variable height of forty to sixty feet.
The water was of variable depth, and half a dozen times the boys suddenly plunged breast deep into a hole, but fortunately did not let go of the canoes.
Forty-two subspecies are recognized, and the species is geographically more variable than any of the other 3 American species.
For each one of several geographically variable features noted, a map was prepared for animals of each sex.
The four adult females seen of alascensis are more variable than those of richardsonii and average smaller in some measurements and larger in others but give no proof of any consistent difference.
In the three instances where the males all were brown and the females all were white, the localities of capture were in the northern part of the variable area.
The same light variablewind continued till ten o'clock next morning, when the trade-wind at east prevailed, and we ventured to ply up to the harbour, first sending a boat to lie in anchorage in the entrance.
It was, however, variable and unsettled for several days, accompanied with dark gloomy weather, and showers of rain.
On the 13th, about eight o'clock in the morning, the wind, which had been variable most part of the night, fixed at S.
In the afternoon we had, for a few hours, variable light airs next to a calm; after which we got a wind from the N.
The wind, at the same time, wasvariable and squally, which obliged the people to attend the decks, so that few in the ships escaped a good soaking.
In these sheltered and shining waters there are scarcely any traces of the recent rough weather, except that the wind still comes in variable puffs, and from all sorts of unexpected directions.
The wind coming in variable gusts, the sails failed to fill at the proper moment, and the White Dove drifted right on to the bows of a great schooner, whose bowsprit loomed portentous overhead.
These, especially the peculiar spectra of the nebulae, of new stars, of variable stars, etc.
Your fat king and your lean beggar is but variable service- two dishes, but to one table.
Haply the seas, and countries different, With variable objects, shall expel This something-settled matter in his heart, Whereon his brains still beating puts him thus From fashion of himself.
