The interpretation timeline
Revelation 1:15 Douay-Rheims

And his feet like unto fine brass, as in a burning furnace. And his voice as the sound of many waters.

A.D. 202 – 1871 7 witnesses

Patristic

before A.D. 750
202
A.D.
Irenaeus Patristic
c. A.D. 130–202
“Thus it was, too, that God formed man at the first, because of His munificence; but chose the patriarchs for the sake of their salvation; and prepared a people beforehand, teaching the headstrong to follow God; and raised up prophets upon earth, accustoming man to bear His Spirit [within him], and to hold communion with God: He Himself, indeed, having need of nothing, but granting communion with Himself to those who stood in need of it, and sketching out, like an architect, the plan of salvation to those that pleased Him. And He did Himself furnish guidance to those who beheld Him not in Egypt, while to those who became unruly in the desert He promulgated a law very suitable [to their condition]. Then, on the people who entered into the good land He bestowed a noble inheritance; and He killed the fatted calf for those converted to the Father, and presented them with the finest robe. Thus, in a variety of ways, He adjusted the human race to an agreement with salvation. On this account also does John declare in the Apocalypse, "And His voice as the sound of many waters." For the Spirit [of God] is truly [like] many waters, since the Father is both rich and great. And the Word, passing through all those [men], did liberally confer benefits upon His subjects, by drawing up in writing a law adapted and applicable to every class [among them].”
Source
303
A.D.
c. A.D. 250–303
“"His feet were like unto yellow brass, as if burned in a furnace." He calls the apostles His feet, who, being wrought by suffering, preached His word in the whole world; for He rightly named those by whose means the preaching went forth, feet. Whence also the prophet anticipated this, and said: "We will worship in the place where His feet have stood." Because where they first of all stood and confirmed the Church, that is, in Judea, all the saints shall assemble together, and will worship their Lord... "And His voice as it were the voice of many waters." The many waters are understood to be many peoples, or the gift of baptism that He sent forth by the apostles, saying: "Go ye, teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost."”
Source

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“And his feet like unto fine brass, as if they burned in a furnace,.... By which is meant, not his human nature in a suffering state; or his people, the meaner and lower parts of his mystical body, in a like state; or his apostles and ministers, who are supporters of his church, and run to and fro with spiritual knowledge, for which, though they suffer much, are permanent and glorious; but either the power of Christ in bearing up and supporting his people, in the care and government and defence of them; or his ways, works, and walks in his churches, and all his providential administrations towards them, which are holy, just, and righteous, and will be manifest; or his wrath and vengeance in treading down and trampling upon his enemies: and his voice as the sound of many waters; meaning his Gospel, as preached by his apostles and ministers, which was heard far and near; see Rom 10:18; and which made a great noise in the world; or his voice of vengeance on his enemies, which will be very terrible and irresistible. Next: Revelation Chapter 2”
Source
1832
A.D.
Adam Clarke Methodist
1762–1832
“His feet like unto fine brass - An emblem of his stability and permanence, brass being considered the most durable of all metallic substances or compounds. The original word, χαλκολιβανον, means the famous aurichalcum, or factitious metal, which, according to Suidas, was ειδος ηλεκτρου, τιμιωτερον χρυσου, "a kind of amber, more precious than gold." It seems to have been a composition of gold, silver, and brass, and the same with the Corinthian brass, so highly famed and valued; for when Lucius Mummius took and burnt the city of Corinth, many statues of these three metals, being melted, had run together, and formed the composition already mentioned, and which was held in as high estimation as gold. See Pliny, Hist. Nat., lib. 34, c. 2; Florus, lib. 2, c. 16. It may however mean no more than copper melted with lapis calaminaris, which converts it into brass; and the flame that proceeds from the metal during this operation is one of the most intensely and unsufferably vivid that can be imagined. I have often seen several furnaces employed in this operation, and the flames bursting up through the earth (for these furnaces are under ground) always called to remembrance this description given by St. John: His feet of fine brass, as if they burned in a furnace; the propriety and accuracy of which none could doubt, and every one must feel who has viewed this most dazzling operation. His voice as the sound of many waters - The same description we find in Eze 43:2 : The glory of the God of Israel came from the way of the east; and his voice was like the noise of many waters: and the earth shined with his glory.”
Source
1849
A.D.
1774–1849
“His feet like unto fine brass, to signify the purity and steadfastness of his steps and actions. — His voice as the sound of many waters, the sound of his preaching by himself, and by his apostles, has been heard throughout all nations of the world. (Witham)”
1871
A.D.
1871
“fine brass--Greek, "chalcolibanus," derived by some from two Greek words, "brass" and "frankincense"; derived by BOCHART from Greek, "chalcos," "brass," and Hebrew, "libbeen," "to whiten"; hence, "brass," which in the furnace has reached a white heat. Thus it answers to "burnished (flashing, or glowing) brass," Eze 1:7; Rev 10:1, "His feet as pillars of fire." Translate, "Glowing brass, as if they had been made fiery (red-hot) in a furnace." The feet of the priests were bare in ministering in the sanctuary. So our great High Priest here. voice as . . . many waters-- (Eze 43:2); in Dan 10:6, it is "like the voice of a multitude." As the Bridegroom's voice, so the bride's, Rev 14:2; Rev 19:6; Eze 1:24, the cherubim, or redeemed creation. His voice, however, is here regarded in its terribleness to His foes. Contrast Sol 2:8; Sol 5:2, with which compare Rev 3:20.”
Source

Undated

date unknown
date
unknown
Glossa Ordinaria Medieval
“And his feet. That is, the last faithful, who by many shakings will not retain their former nature, like fine brass, which is often set on fire, and takes a better colour. In a burning furnace. In another translation there is had: with the fine brass of Libanus, by which it is shown that in that region where the Lord was crucified that tribulation is especially to prevail. And his voice as the voice of many waters. That is, his preaching obtains the power of water, because it cleanses. Or, because many peoples have now received this voice (who are compared to water on account of their flowing), so much the more ought you to stand firm. Or, a voice that gives many waters, that is, graces, whence there presently follows:”
Source
Modern · 1953 →

The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.