Contrary to the last, which may be considered as belonging to the day, this is properly the cloud of night, the time of its first appearance being about sun-set. It compre. hends all those creeping mists which in calm evenings ascend in spreading sheets (like an inundation of water) from the bottom of valleys, and the surfaces of lakes, rivers, &c. &c. Its duration is frequently through the night.

On the return of the sun, the level surface of this cloud begins to put on the ap. pearance of cumulus, the whole at the same time separating from the ground. The continuity is next destroyed, and the cloud ascends and evaporates, or passes off with the appearance of the nascent cumulus.

This has been long experienced as a prognostic of fair weather, and indeed there is none more serene than that which is ushered in by it. The relation of the stratus to the state of the atmosphere, as indicated by the barometer, &c. appears notwithstanding

VOL. IV.

tion.

OF THE CIRRO-CUMULUS.-The cirrus

having continued for some time increasing or stationary, usually passes either to the cirrocumulus or the cirro-stratus, at the same time descending to a lower station in the atmosphere.

The cirro-cumulus is formed from a cirrus, or from a number of small separate cirri, by the fibres collapsing as it were, and passing into small roundish masses, in which the texture of the cirrus is no longer discernible, although they still retain somewhat of the same relative arrangement, as exhibited by the following figure. (See next page.)

This change takes place either through. out the whole mass at once, or progressively from one extremity to the other. In ei ther case the same effect is produced on a number of adjacent cirri at the same time, and in the same order. It appears in some instances to be accelerated by the approach of other clouds.

This modification forms a very beautiful sky, sometimes exhibiting numerous dis tinct beds of these small connected clouds, floating at different altitudes.

The cirro-cumulus is frequent in summer, and is attendant on warm and dry weather.

ter.

It may either evaporate or pass to the cirrus or cirro-stratus.

OF THE CIRRO-STRATUS.-This cloud ap. pears to result from the subsidence of the fibres of the cirrus to a horizontal position, at the same time that they approach towards each other laterally. The form and relative position, when seen in the distance, frequent.

this, as in other instances, the structure must be attended to rather than the form, which varies much, presenting at other times the appearance of parallel bars, interwoven streaks, like the grain of polished wood, &c. It is always thickest in the middle, or at one extremity, and extenuated towards the edge, as represented by the following figure.

The distinct appearance of a cirrus does not always precede the production of this and the last modification.

The cirro-stratus precedes wind and rain, the near or distant approach of which may sometimes be estimated from its greater or less abundance and permanence. It is almost always to be seen in the intervals of storms. Sometimes this and the cirro-cumu. lus appear together in the sky, and even al ternate with each other in the same cloud, when the different evolutions which ensue are a curious spectacle, and a judgment may be formed of the weather likely to ensue, by observing which modification prevails at

last. The cirro-stratus is the modification which most frequently and completely exhi bits the phenomena of the solar and lunar halo, and (as supposed from a few observations) the parhelion and paraselene also. Hence the reason of the prognostic for foul weather, commonly drawn from the appearance of the halo.

OF THE CUMULO-STRATUS.-The different modifications which have been just treated of sometimes give place to each other,

More rarely the cumulus alone performs this evolution, and its superior part constitutes the incumbent cirro-stratus.

In either case a large lofty dense cloud is formed, which may be compared to a mushroom, with a very thick short stem. But when a whole sky is crowded with this modification, the appearances are more indistinct. The cumulus rises through the interstices of the superior clouds, and the whole, seen as it passes off in the distant horizon, presents to the fancy mountains covered with snow, intersected with darker ridges, and lakes of water, rocks, and tow. ers, &c.

The distinct cumulo-stratus is formed in the interval between the first appearance of the fleecy cumulus and the commencement of the rain, while the lower atmosphere is yet too dry; also, during the approach of thunder storms; the indistinct appearance of it is chiefly in the longer or shorter intervals of showers of rain, snow, or hail.

The cumulo-stratus chiefly affects a mean state of the atmosphere as to pressure and temperature, but in this respect, like the other modifications, it affords much room for future observation.

OF THE NIMBUS, OR CUMULO-CIRRO-STRA. TUS.-Clouds, in any of the preceding modi.

fications, at the same degree of elevation, or in two or more of them, at different elevations, may increase so as completely to obscure the sky, and at times put on an appear. ance of density, which, to the inexperienced observer, indicates the speedy commence. ment of rain. It is nevertheless extremely probable, as well from attentive observation as from a consideration of the several modes of their production, that the clouds, while in any one of these states, do not at any time let fall rain.

Before this effect takes place, they have been uniformly found to undergo a change, attended with appearances sufficiently remarkable to constitute a distinct modifica. tion, which is represented by the following figure, called the Nimbus, or Cumulo.cirro. stratus cloud. (See next page.)

In this figure a shower is represented as coming from behind an elevated point of land.

The nimbus, although in itself one of the least beautiful clouds, is yet now and then superbly decorated with its attendant, the rainbow, which can only be seen in perfec tion when backed by the widely extended uniform gloom of this modification.

The relations of rain, and of periodical showers more especially, with the varying temperature, density, and electricity of the atmosphere, will probably now obtain a fuller

investigation, and with a better prospect of success than heretofore.

Remarks on the Rival Claims to the Introduction of Steam Navigation. [From the London Mechanics' Magazine.]

SIR,-It must be evident to every one, that not only England, but the whole of the civilized world, is under immense obligations to the individual who first rendered steam available to the purposes of navigation. Pub. lic opinion, however, seems still to vibrate between the conflicting claims to this honor put forward by the late William Symington, Mr. Miller, of Dalswinton, (or rather by his representatives on his behalf,) and Mr. Jas. Taylor. As to those of Fulton* and Bell, they seem, according to common consent, to be wholly untenable.

We will, if you please, begin "wi' the laird" first. Mr. Miller was a man of property, possessed of an active mind, which was constantly requiring excitement. He was, therefore, always ready to enter into any experiments which promised to afford him that mental stimulus congenial to his feelings. He was, consequently, very rea. dy to assist with his patronage young men who possessed inventive genius, or supposed that they were so blessed, and, of course, was very commonly disappointed. As he was easily induced to begin experimentaliz. ing, he was just as apt to quit it without car. rying it on to a successful result. For, al. though not deficient in wealth, he lacked that spirit of perseverance from which alone

success can emanate.

We shall shortly have something more to say on this subject. Fulton most certainly had some claims to what extent we shall examine shortly.-[ED. AM. M. M.]

Taylor was a tutor in this Mr. Miller's family. He had been on terms of intimacy with William Symington, when at the University of Edinburgh, and had seen a model of an improvement which Symington (though then still a very young man) had just perfected in the steam engine. In consequence, it would seem, of some mention made to Mr. Miller of Symington, (very probably by Tay. lor,) Mr. Miller, early in 1786, called upon Symington, who was then in the employment of, and residing with, Mr. Gilbert Meason, the manager of the Wanlock-Head Mining Company, and after conversing with him for some time, engaged him to make some expe. riments, for the purpose of ascertaining the practicability of propelling boats by steam. Miller himself had, previously to this, attempted to move boats by means of wheels, set in action by treddles, a plan which he was compelled to abandon from the excessive fatigue it occasioned to the men em. ployed. This scheme, by the way, had not even the charm of novelty to recommend it, for it had been practised by the Romans, who used oxen to work machinery; and also by Savary, who had, like Mr. Miller, exerted human force for that purpose.*

The biographer of Taylor, in " Chambers' Journal," states that he "attended the University of Edinburgh for several years;" that the classes selected by him were anatomy, surgery, and chemistry; and that he "prose

* Mr. Miller seems to have had a predilection for appropriating other persons' inventions to himself; or, if he had not, his friends have endeavored to do so for him, as they would willingly have us to believe that the piece of sea ord. nance, known as the carronade, was the fruit of Mr. Miller's genius, when, in fact, it was invented by Mr. Gascoigne, one of the proprietors and managers of the Carron Iron Works, from which circumstance it derived its name.