Ego etsi hoc etiam modo ova excludi posse ratio loqui videtur: video tamen aliud sensisse Democritum, verbis eius Graecis diligentius examinatis, et placet gastran vas ventricosum vertere, ut prius in tale vas intelligamus fimum inijciendum, tum super fimo imponendas plumas (ut ἐπίβαλλε potius quam περίβαλλε legatur) in plumis ova: postremo rursus fimum addendum donec contegantur ova. Sed ut ut est, Porta hoc a se diligentissime expertum non successisse scribit, nec quomodo succedere possit, sese conijcere posse. Hoc etiam addens quod qui clibanum laudant, modum non ostendant quo id fieri possit. Unde quae ipsemet fecit, et ab aliis factitata vidit minutissime demonstrat[1].

As far as I am concerned, although reason seems to suggest that eggs can hatch also in this manner, nevertheless I reckon that Bolos of Mendes, after his Greek words have been more careful checked, he meant another thing, and it is my opinion to translate gástran with vas ventricosum - bellied pot, since I mean that dung must first be thrown into it, afterwards feathers are to be placed upon the dung (reading epíballe - put on - rather than períballe - put around) and the eggs within the feathers: lastly further dung must be added until eggs are covered. But however that may be, Giambattista Della Porta writes that this, tested by him with a lot of diligence, has not been followed by success, and that he himself cannot gather how it could be successful. He is also adding that those who are praising the oven do not give account for the way thanks to which it can happen. Hence he is describing down to the smallest detail what he himself has done and what he saw done usually by others.

Ut parvo labore, et sine Gallinis quivis ova clibano calido excludere possit, vas fieri vult ligneum, valde simile dolio, rotundum, cuius diameter tantae sit longitudinis, quantum capiat brachium intromittendum, ut ova componere, et convertere possit: altitudo quatuor pedum[2]. Hoc tribus tabulatis intus, in quatuor partes dividemus. Sit primum sexquipedale, secundum paulo maius pede, tertium pedale, quartum omnium minimum. Habeat unaquaeque cellula tabulatis divisa suum ostiolum latitudine quantum brachium immitti possit, suaque opercula, ut apte claudi, et reserari possint. Primum, et secundum tabulatum ex tenuibus tabellulis, vel viminibus contexta sint; tertium sit aeneum, fornicatum, postremum ligneum, solidumque. Primum et secundum tabulatum in centro foramen habeat, latitudinis trium digitorum, per quod aeneus canalis, vel ferreus, stanno sublitus. Is supra secundum tabulatum ad medium pedem semper emineat, sic et in inferiori, sed in imo patentioris fiat oris ad modum pyramidis, vel infundibuli, ut concinne calorem, et flammam suppositae lucernae excipere possit. In secundo tabulato canalis circa supremum locum perforatus sit, ut inde exhalans calor, locum tepide foveat, et ova ex superiori parte calescant, ut Gallinae faciunt.

In order that with little labor and without hens anyone can hatch eggs by a heated portable oven, he should make a wooden vessel very similar to a barrel, round, with a diameter long enough to receive an arm thrust into it, so that one may place eggs within it and turn them over: it should be four feet high. When three floors are arranged inside, it will be divided into four parts. The first space should be a foot and a half in height, the second hardly more than a foot, the third a foot, the fourth the lowest of all. Each compartment, so divided by floors, must have a little its own opening wide enough to receive the arm thrust through it, as well as a little door so the compartment can be fairly closed and opened. The first and second floors should be made of thin slats or of interwoven wickers; the third should be of bronze and arched, the last of solid wood. Let the first and second floors have a hole in the center, three fingers wide, through which there is a bronze or a tin-plated iron pipe. The pipe should ever project half a foot above the second floor, so in the lower floor too, but at the bottom let it have a widened mouth in the shape of a pyramid or funnel, so that it can receive evenly the heat and the flame of a lantern placed beneath. In the second floor let the pipe be perforated at the top so that the heat exhaling from it warms this place, and the eggs get warm from above as hens do.

Super haec tria tabulata spargatur scobs lignea, quae tibi aptissimo operi videbitur. Scobs circa dolii latera erectior, in medio minus: in imo, ubi canalis, depressior, ut ova supra eam incubantia calorem undique a canali provenientem excipiant. In tertio tabulato, ubi canalis terminatur, sit circa latera depressa, in medio circa canalem altior: supra scobem linteus extendatur subtilis, si deturpatur, ut denuo lavari possit, et exclusi pulli supra illum ambulare possint.

Above these three floors scatter sawdust which will come in very useful for you. Let the sawdust be higher around the sides of the barrel, less in the middle: at the center, where the pipe is, let it be even lower, so that the eggs incubating upon the sawdust may receive on all sides the warmth coming from the pipe. On the third floor, where the pipe ends, the sawdust should be pressed down around the sides, higher in the center around the pipe: spread a thin linen cloth, which can be washed if it becomes soiled, upon the sawdust, so that the hatched-out chicks may walk around on it.

Singulis tabulis centena ova accomodentur, plus, minus. Retusa ovi pars infra, acuta sursum vergat. Parietes dolii supra scobem extantes intra cellulas, et superna pars tabulati, ovillis pellibus contegantur, ut suo tepore calorem retineant. Inferiori cellula sub infundibulo lucerna accomodetur accensa, in initio binis {ellichniis} <ellychniis>, in fine tribus aestatis tempore, sed hyeme initio tribus, postremo quatuor, aut quinque. Feriat lumen in medio infundibuli, ut per canalem ascendens calor, aeque cellulas concalfaciat.

Let arrange on each floor one hundred eggs, more or less. The blunt end of the eggs must turn downward, the sharp end upward. Inside the compartments, cover the barrel’s walls sticking above the sawdust as well as the supreme part of the floor, with sheepskins, so that they retain the warmth by their insulating power. Place a lighted lantern in the lower compartment under the funnel, and in summer, in the beginning, with two wicks, with three wicks towards the end, but in winter in the beginning with three and in the end with four or five wicks. Let the flame strike the middle of the funnel so that the heat ascending through the pipe can evenly warm the compartments.

Locus in quo hoc vas steterit, sit tepidus, et solitarius. In inferiori parte, ubi accensa lucerna non oportet ova accomodare, quia calorem non habet ad ova excludenda aptum. Sed ubi pulli madidi, quam primum ovis excluduntur, hic claudantur, ut tepido flammae calore madorem ex<s>iccent: bis, terve singulis diebus animadvertendo, si calor remissus, tepens, aut intensus sit. Quod ita cognoscemus: ovum e cellula extrahemus, ut supra oculum ponendo optime experiemur. Nam si offendit, intensus est: si insensibilis, remissus. Intensus calor excoquit ova, remissus irrita facit. Ob id lucerna lumen addendo, et minuendo exaequatum reddes.

Let the place in which this vessel stands be lukewarm and solitary. Eggs should not be placed in the lower part where the lighted lantern is, because it does not have a heat suitable for hatching eggs. But as soon as the chicks hatch out from eggs and are still moist they must be shut up here, so that with the tepid heat of the flame they dry up their moisture, checking carefully twice or thrice each day to find out whether the heat is low, lukewarm, or intense. You can find out that as follows: take an egg from a compartment and placing it on an eye you will realize in the best way. For if it troubles you, the heat is intense: if it does not give any feelings, the heat is low. Intense heat bakes the eggs, low heat makes them worthless. Because of this you will make the heat even by the lantern, raising or lowering the fire.

Post quartum diem, a quo ova fieri coeperint, extrahito e cella, et nulla facta commotione vehementi, sensim contra splendorem Solis, vel candelae quispiam speculabitur, si prolificum sit ovum, necne. Nam si fibrarum aliquot, cruentumque discurrere videtur, prolificum est, si contra perspicuum erit, ceu infoecundum reijciendum: irriti loco substituatur aliud. Foecunda oportet quotidie ad calorem luminis vertere, atque circumcirca movere, ut Gallina solet. Nec verendum nobis ne corrumpantur ova, vel si ab aliquo sensim, et commode pertractentur.

After the fourth day since eggs begun to develop draw out them from the compartment and without any violent motion someone will examine them little by little against the shining light of the sun or of a candle to see whether the egg is fertile or not. For if some of the bloody fibers are seen to move it is fertile, but if the egg is limpid, or infertile, it must be discarded: another egg should take place of the infertile one. Daily the fertile eggs ought to be turned towards the heat of the lantern and ought to be turned over, as usually the hen does. And there is no need to fear the eggs will become corrupt, especially if they are handled gently and suitably by someone.

Post decimum nonum, vel vigesimum diem aestatis tempore, aut vigesimum quintum, aut vigesimum octavum hyemis, ova manu capies, ac Soli obversa inspice, ubi pulli rostrum steterit, ibi crustam rumpito, et per ovi foramen manibus rostellum capiendo pulli caput foras extrahe, ac suo loco repone. Nam ex se ipso foras progreditur, et ovo egressum in inferiori cellula, ut diximus, pone, sed a pavimento lucerna aliquantulum absit, ne pulli lucis splendore allecti, lumen rostellis feriant, et comburantur. At si quae diximus diligenter operatus fueris, ex trecentis ovis vix decem, aut viginti perdes. Hactenus itaque Io. Bap. Porta.

After the nineteenth or twentieth day in summer, or the twenty-fifth or twenty-eighth in winter, take the eggs in your hand and inspect them, turning them to the sun, and where the chick’s beak is located, here break the shell, and seizing with hands the little beak through the hole in the egg pull out the head of the chick, and then put the egg back in its place. For the chick comes out by himself, and, after he came out from the egg, place him, as already I said, in the lower cell, but the lantern must be a little bit raised from the floor so that the chicks may not strike the lantern with their little beaks, attracted by the brightness of the light, and thus burn themselves. Only if you will carefully do what I said you will hardly lose ten or twenty eggs out of three hundred. Thus far then Giambattista Della Porta.

Petrus Crescentiensis[3] denique scribit, in quadam regione homines reperiri, qui furnos ita temperate calefaciant, ut eorum calor par sit Gallinae incubantis, et in furno, seu {clibamo} <clibano> ponere {quamplurimos} <quamplurimas> plumas, et mille Gallinacea ova quae post viginti dies nascantur, ac erumpant. Atque istaec de iis, quae ad huiusce avium [228] generis procreationem spectabant dicta sint.

Pier de’ Crescenzi finally writes that in a certain region there are men who heat up ovens so moderately that their heat is equal to that of an incubating hen, and into this oven or furnace they place plenty of feathers and a thousand hen eggs which after twenty days get birth, and hatch out. Thus much then about details concerning the procreation of this kind of birds.