And thus I saw the horses in the vision, and them that sat on them, having breastplates of fire, and of jacinth, and brimstone: and the heads of the horses were as the heads of lions; and out of their mouths issued fire and smoke and brimstone.

And thus I saw the horses in the vision, and them that sat on them, having breastplates as of fire and of hyacinth and of brimstone: and the heads of lions; and out of their mouths proceedeth fire and smoke and brimstone.

And thus I saw the horses in the vision: and they that sat on them, had breastplates of fire and of hyacinth and of brimstone, and the heads of the horses were as the heads of lions: and from their mouths proceeded fire, and smoke, and brimstone.

And thus I saw the horses in the vision, and those that sat upon them, having breastplates of fire and jacinth and brimstone; and the heads of the horses were as heads of lions, and out of their mouths goes out fire and smoke and brimstone.

And thus I saw the horses in the vision, and them that sat on them, having breastplates as of fire and of hyacinth and of brimstone: and the heads of the horses are as the heads of lions; and out of their mouths proceedeth fire and smoke and brimstone.

And thus I saw the horses in the vision, and them that sat on them, having breast-plates of fire, and of jacinth, and brimstone: and the heads of the horses were as the heads of lions: and out of their mouths issued fire, and smoke, and brimstone.

And thus I saw the horses in the vision, and those sitting upon them, having breastplates of fire, and jacinth, and brimstone; and the heads of the horses are as heads of lions, and out of their mouths proceedeth fire, and smoke, and brimstone;

And this was the appearance of the horses which I saw in my vision - and of their riders. The body-armour of the riders was red, blue and yellow; and the horses' heads were shaped like the heads of lions, while from their mouths there came fire and smoke and sulphur.

And so I saw the horses in the vision, and those who were seated on them, having breastplates of fire and glass and of burning stone: and the heads of the horses were as the heads of lions; and out of their mouths came fire and smoke and a smell of burning.

And I also saw the horses in the vision. And those who were sitting upon them had breastplates of fire and hyacinth and sulphur. And the heads of the horses were like the heads of lions. And from their mouths proceeded fire and smoke and sulphur.

And this is what the horses and their riders appeared to be like in my vision: – They had breastplates of fire, blood-red and sulphurous, and the heads of the horses were like lions' heads, while out of their mouths issue fire, and smoke, and sulfur.

And thus I saw the horses in the vision - That is, he saw them as he proceeds to describe them, for the word "thus" - οὕτως houtōs - refers to what follows. Compare Robinson's Lexicon on the word (b), and see Matthew 1:18; Matthew 2:5; John 21:1; Hebrews 4:4. Prof. Stuart, however, refers to what precedes. The meaning, as it seems to me, is, that he fixed his attention on the appearance of the immense army - the horses and their riders, and proceeded to describe them as they struck him.
And them that sat on them - He fixed the attention on horse and rider. Their appearance was unusual, and deserved a particular description.
Having breastplates of fire - That is, those who sat on them had such breastplates. The word rendered here as "breastplate" denoted properly a coat of mail that covered the body from the neck to the thighs. See the notes on Ephesians 6:14. This would be a prominent object in looking at a horseman. This was said to be composed of "fire, and jacinth, and brimstone"; that is, the part of the body usually incased in the coat of mail had these three colors. The word "fire" here simply denotes red. It was burnished and bright, and seemed to be a blaze of fire. The word "jacinth" - ὑακινθίνους huakinthinous - means "hyacinthine." The color denoted is that of the hyacinth - a flower of a deep purple or reddish blue. Then it refers to a gem of the same color, nearly related to the zircon of the mineralogists, and the color mentioned here is deep purple or reddish blue. The word rendered "brimstone" - θειώδης theiōdēs - means properly "sulphurous," that is, made of sulphur, and means here simply yellow. The meaning of the whole then is, that these horsemen appeared to be clad in a special kind of armor - armor that shone like fire, mingled with blue and yellow. It will be necessary to look for the fulfillment of this in cavalry that was so caparisoned.
And the heads of the horses were as the heads of lions - Resembled, in some respects, the heads of lions. He does not say that they were the heads of lions, or that the riders were on monsters, but only that they, in some respects, resembled the heads of lions. It would he easy to give this general appearance by the way in which the head-dress of the horses was arrayed.
And out of their mouths issued - That is, appeared to issue. It is not necessary to understand this as affirming that it actually came from their months, but only that, to one looking on such an approaching army, it would have this appearance. The pagan poets often speak of horses breathing out fire and smoke (Virgil, Geor. vol. ii. p. 140; iii. 85; Ovid, Met. vol. vii. p. 104), meaning that their breath seemed to be mingled smoke and fire. There is an image superadded here not found in any of the classic descriptions, that this was mingled with brimstone. All this seemed to issue from their mouths - that is, it was breathed forth in front of the host, as if the horses emitted it from their mouths.
Fire and smoke and brimstone - The exact idea, whether that was intended or not, would be conveyed by the discharge of musketry or artillery. The fire, the smoke, and the sulphurous smell of such a discharge would correspond precisely with this language; and if it be supposed that the writer meant to describe such a discharge, this would be the very language that would be used. Moreover, in describing a battle nothing would be more proper than to say that this appeared to issue from the horses' mouths. If, therefore, it should be found that there were any events where firearms were used, in contradistinction from the ancient mode of warfare, this language would be appropriate to describe that; and if it were ascertained that the writer meant to refer to some such fact, then the language used here would be what he would adopt. One thing is certain, that this is not language which would be employed to describe the onset of ancient cavalry in the mode of warfare which prevailed then. No one describing a charge of cavalry among the Persians, the Greeks, or the Romans, when the only armor was the sword and the spear, would think of saying that there seemed to be emitted from the horses' mouths fire, and smoke, and brimstone.

Breastplates of fire - jacinth, and brimstone - That is, red, blue, and yellow; the first is the color of fire, the second of jacinth, and the third of sulphur.
And the heads of the horses - Is this an allegorical description of great ordnance? Cannons, on the mouths of which horses' heads were formed, or the mouth of the cannon cast in that form? Fire, smoke, and brimstone, is a good allegorical representation of gunpowder. The Ottomans made great use of heavy artillery in their wars with the Greeks of the lower empire.

And thus I saw the horses in the vision, and them that sat on them,.... In such numbers, and with horsemen on them, and in such order, and in appearance, as follows:
having breastplates of fire, and of jacinth and brimstone; which may be understood either literally of their external breastplates, which being of polished iron, according to the custom of these people, looked at a distance like sparkling fire, and seemed to be of the colour of hyacinth, or of a sky colour, and appeared as flaming sulphur; though some think that their breastplates were of different colours, some looked like fire, others like jacinth, and others like brimstone; or it may denote that they would be accoutred in scarlet, blue, and yellow, which are the colours the Turks have commonly wore; or this may be understood of their internal breastplates, and the disposition of their minds, having in their breasts nothing but wrath, fury, desolation, and destruction; a fire devoured before them, and behind them a flame burned:
and the heads of the horses were as the heads of lions: gaping and roaring for their prey, or all bloody with it, and looked fierce, and savage, and terrible: this designs not so much the strength, boldness, and intrepidity of their horses, which are warlike creatures, and very undaunted in battle, as of the men that sat upon them, who were like David's heroes and warriors, 1-Chronicles 12:8.
And out of their mouths issued fire, and smoke, and brimstone; which may be referred either to the horses, or to the horsemen, or both: some interpret this allegorically, and by "fire" understand either the tyranny of the Turks over their own people, or their fury against others, or their blasphemy against God, and Christ, and his people, being like so many railing Rabshakehs against the God of the Christians; and by "smoke" the false doctrine of Mahomet, which came out of the same bottomless pit the doctrine of the Romish antichrist did; and is fitly compared to smoke for its disagreeableness, darkness, levity, and duration; See Gill on Revelation 9:2; and by "brimstone" the immorality and sad corruption of manners among the Turks, and what is allowed of, or winked at, as fornication, polygamy, sodomy, &c. but rather this is to be taken more literally, and represents the firing of guns on horseback in battle. Guns are a late invention, and the use of them was found out in the age this trumpet refers to; and were much made use of by the Turks in their wars, and particularly great guns or cannons; these were used by Amurath at the sieges of Belgrade, and of Constantinople (m); and by Mahomet the Second at the taking of Constantinople, where a gun or cannon was used of that size, as to be drawn by seventy yoke of oxen, and two thousand men (n). Gunpowder set on fire is fitly signified by fire, smoke, and brimstone, which is made of nitre, charcoal, and brimstone; and the firing of guns on horseback is most aptly described by these coming out of the mouths of horses and horsemen: nor could it well appear to John to be otherwise, who could never have seen a gun, and one fired off in his life; nor could he well represent to others what he saw in vision, than in this manner.
(m) Chalcocond. l. 5. p. 152, 163. (n) Chalcocond. l. 8. p. 252.

thus--as follows.
of fire--the fiery color of the breastplates answering to the fire which issued out of their mouths.
of jacinth--literally, "of hyacinth color," the hyacinth of the ancients answering to our dark blue iris: thus, their dark, dull-colored breastplates correspond to the smoke out of their mouths.
brimstone--sulphur-colored: answering to the brimstone or sulphur out of their mouths.