I cannot say for sure, but it seems that this 18th century Porter recipe is describing first wort hopping.
To brew Porter in a Private Family (1773)
Then bruise four pound of hops between the hands; and tie them up in a bag ; put them into the receiver or under-back, and let the wort run out upon them in a fine, small stream. When this is running, stir up the fire under the copper, and make the remaining water considerably hot ; then run it on upon the grains, when the other is nearly run off ; and, after stirring them well about, cover the mash-tub, and let them stand two hours more.