The first piece of the tabernacle's furniture, for which precise directions were delivered. Exod 25. I.
It appears to have been an oblong chest of shittim (acacia) wood, 2 1/2 cubits long by 1 1/2 broad and deep. Within and without gold was overlaid on the wood, and on the upper side or lid, which was edged round about with gold, the mercy-seat was placed. The ark was fitted with rings, one at each of the four corners, and through these were passed staves of the same wood similarly overlaid, by which it was carried by the Kohathites. (Numbers 7:9; 10:21) The ends of the staves were visible without the veil in the holy place of the temple of Solomon. (1 Kings 8:8) The ark, when transported, was enveloped in the "veil" of the dismantled tabernacle, in the curtain of badgers' skins and in a blue cloth over all, and was therefore not seen. (Numbers 4:5,20) II. Its purpose was to contain inviolate the divine autograph of the two tables, that "covenant" from which it derived its title. It was also probably a reliquary for the pot of manna and the rod of Aaron, and you can find more about that here on st-takla.org on other commentaries and dictionary entries.III.
Before David's time its abode was frequently shifted. It sojourned among several, probably Levitical, families, (1 Samuel 7:1; 2 Samuel 6:3,11; 1 Chronicles 13:13; 15:24,25) in the border villages of eastern Judah; and did not take its place in the tabernacle, but dwelt in curtains, i.e. in a separate tent pitched for it in Jerusalem by David. Subsequently the temple, when completed, received, in the installation of the ark in its shrine, the signal of its inauguration by the effulgence of divine glory instantly manifested. It was probably taken captive or destroyed by Nebuchadnezzar, 2 Esdr. 10:22, so that there was no ark in the second temple.
Main reference: Smith's Bible Dictionary (1860s)
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