GEVURAH: YESHIVAT HAVERIM יְשִׁיבָה חברים – BABYLONIAN TALMUD p74

MISHNA VII.: It is not permitted to place a vessel under a lamp so that the oil of the lamp drip
into it. If a vessel was placed under a lamp before the Sabbath set in, it may remain there; but
the use of such oil on the same Sabbath is not permitted, as it was not previously prepared.
GEMARA: Said R. Hisda: “Although it was said that the placing of a vessel under a hen (laying
on sloping ground) to receive the egg is forbidden, yet to cover the egg so as to prevent it from
being crushed is permitted.”
Said Rabba: The reason of R. Hisda is because he holds that hens being in the habit of laying
eggs on level ground, in order to prevent the egg from being stepped upon, it is permitted to
cover it with a vessel; but as liens are not in the habit of laying eggs on sloping ground, the
placing of a vessel under the hen to receive the egg was not allowed.
Abayi objected to this, stating: “Were we not taught in the Mishna that it is permitted to place a
vessel under a lamp in order to take up the (dropping) sparks?” (This seldom occurs and
therefore it is permitted.) He was told that the dropping of sparks by a lamp is also of frequent
occurrence.
R. Joseph, commenting on the statement of R. Hisda, gave another reason–viz.: That the vessel
(placed under a hen to receive an egg) is made useless for that same Sabbath.
Abayi raised the same objection, (intending to) prove by it that the vessel placed under a lamp is
also made useless on that same Sabbath, and R. Huna b. R. Joshua answered: “Sparks have
nothing substantial about them (therefore the vessel containing them is not made useless on the
same Sabbath).”
R. Itz’hak said: In the same manner as it is not permitted to place a vessel under a laying hen, so
is it also not permitted to cover the egg laid; for the reason that a vessel must not be handled on
the Sabbath except for the use of such things as are themselves permitted to be handled on the
Sabbath.
All the objections of Abayi being raised against R. Itz’hak’s statements, he answered: “In that
case there was a lack of space.” (If the space occupied by a vessel is needed, that vessel
may be removed, and while being removed may be used for any purpose.)