294 U.S. 1 (1935), 102, Smith v. Snow

Docket Nº:No. 102
Citation:294 U.S. 1, 55 S.Ct. 279, 79 L.Ed. 721
Party Name:Smith v. Snow
Case Date:January 07, 1935
Court:United States Supreme Court

Page 1

294 U.S. 1 (1935)

55 S.Ct. 279, 79 L.Ed. 721




No. 102

United States Supreme Court

Jan. 7, 1935

Argued December 3, 4, 1934




1. Claim 1 of the Smith Patent, No. 1,262,860, for a method for the incubation of eggs, held valid, and infringed. P. 7.

2. Claim 1 covers broadly the essential elements of the Smith invention, viz., (a) the arrangement of the eggs at different levels in staged incubation in a closed chamber, having restricted openings of sufficient capacity for the escape of foul air without undue loss of moisture; (b) the application to the eggs of heated air in a current created by means other than variation of temperature, and (c), as marking the boundaries of the claim, a sufficient velocity in the current to circulate and diffuse the air and maintain it throughout the chamber at substantially the same temperature, whereby the air will be vitalized, moisture conserved, and the units of heat carried from the eggs in the more advanced stage of incubation to those in a less advanced stage.


(1) The claim is not limited by the particular mode of use described in the specifications, since the claims of the patent, not its specifications, measure the invention. P. 11.

(2) Examination of the claim in the light both of scientific fact and of the particular form in which the inventor reduced it to practice as described in the specifications makes it plain that the claim does not require any particular order or arrangement of the eggs in staged incubation in the incubator, or that the propelled air current

Page 2

should reach them in any particular order, or that it should be guided, controlled, or directed by any particular means, or in any particular manner other than that it should be of sufficient velocity to produce the results prescribed by the claim. Pp. 9, 13.

(3) There is nothing in the file wrapper to suggest that any addition was made to Claim 1 to restrict the patent to any particular order of arrangement of the eggs or any particular direction or means of control of the current of air, other than its velocity, and nothing to estop the patentee from asserting that the claim is not restricted by such features. P. 14.

(4) The claim is not limited by the prior art. P. 16.

(5) The invention as claimed was infringed by respondents' apparatus in this case. P. 18.

3. The fact that a claim broadly covering the essentials of an invention omits particular means of application which are called for by other claims is evidence that the broader claim was not intended to be so restricted. P. 13.

4. The inventor of a novel method of artificial incubation of eggs, which solved the major problems of that art in a highly efficient manner and was attended by great practical and commercial success, is entitled to broad claims in his patent, and to a liberal construction of them tending to secure to the patentee the benefit of his invention, rather than to defeat the grant. P. 14.

5. A broad claim is not to be given a restricted construction because its allowance in the Patent Office followed the rejection of narrow claims. P. 16.

6. The invention of a combination is not anticipated by earlier and impracticable experiments for the same end with isolated elements of the combination. P. 17.

70 F.2d 564 reversed.

Certiorari to review a decree reversing a decree of the District Court and holding valid, but not infringed, a claim of a patent for an improved apparatus and method for the incubation of eggs.

Page 3

STONE, J., lead opinion

MR. JUSTICE STONE delivered the opinion of the Court.

Certiorari was granted to review a decree of the Circuit Court of Appeals for the Eighth Circuit, [55 S.Ct. 280] 70 F.2d 564, which reversed the decree of the District Court and held valid, but not infringed, the first claim of the Smith patent, No. 1,262,860, of April 16, 1918, for an improved apparatus and method for the incubation of eggs.1 The Court of Appeals for the Ninth Circuit held the same claim valid and infringed in Waxham v. Smith, 70 F.2d 457, in which case certiorari was also granted. The question thus presented is one of the scope of the claim.

Only so much of the patent as relates to a method for incubation is now involved. Correct appreciation of the contentions made requires a brief exposition of the well known phenomena which attend the incubation of eggs under natural conditions.

The period for hatching eggs of the domestic hen is twenty-one days. The eggs are cold at the beginning of the period of incubation, although at that time generation has already progressed slightly. Continuation of this process and successful incubation depend upon the

Page 4

application of heat to the eggs, and the maintenance of their temperature at not less than body heat, about 100° F. and not more than 105° F. Any substantial divergence from this range of temperature results in deterioration or death of the embryo, and consequent failure of the hatching process. If the temperature is maintained within this range, the eggs, during the first ten days of the period, absorb heat required to generate and maintain the life of the embryo. The eggs are then said to be endothermic, or heat absorbing. From the eleventh day until the end of the period, the embryo has developed to a point at which the egg generates more heat than is needed to keep the embryo alive. They are then said to be exothermic. From that time on, the excess heat is given off to the surrounding air or to objects in contact with the eggs, if at a lower temperature than the eggs.

The development of heat accompanies the oxidation of food elements within the egg, in consequence of which it gives off carbon dioxide during the period of incubation and absorbs oxygen from the external air, both of which pass through the shell of the egg and its lining membrane. During the period of incubation, there is also gradual evaporation of moisture from the egg, which tends to reduce its temperature slightly. The best results are obtained if the total evaporation during incubation does not exceed about 15%. Evaporation in excess of that amount affects the embryo adversely; the chick when hatched being undeveloped and lacking normal strength.

Successful artificial incubation therefore involves conformity to three principal requisites: the maintenance of proper temperature during the period of incubation, the prevention of excessive evaporation of moisture, and the supply of an adequate amount of oxygen, which involves also the removal from the incubator of the carbon dioxide which results from oxidation of the contents of the egg.

Page 5

The artificial incubation of eggs is an ancient art. It appears to have been known to the Egyptians two thousand years ago, and for a comparable period to the Chinese. Until Smith, the patentee, carried on his experiments, the effort had been generally to reproduce as nearly as practicable the natural conditions of incubation. In practice, eggs, in relatively small numbers, seldom more than 300, and usually less, were placed on the same level in a cabinet with heating means above the eggs, so that the temperature above the eggs was maintained at a higher point -- about 103° F. -- than that below. To secure the requisite exposure of the eggs to the higher temperature, it was necessary in the course of incubation to turn the eggs frequently, as is done by the hen in nature. Provision was made for supplying fresh air to [55 S.Ct. 281] the cabinet and for humidifying the air within the cabinet. All incubators were of the still air type -- that is to say, the only movement of air within the incubator was that caused by variations of temperature at different points within the cabinet, resulting in some transmission of heat by radiation or convection. The opinion seems to have prevailed that the presence of currents of air either within or surrounding the cabinet was harmful. Successful operation of this method required nice adjustments of the heating means so as to avoid overheating as the eggs passed into the more advanced stages of incubation, reaching their highest temperature about the seventeenth day.

Smith, conceived the idea, embodied in his patent, of setting the eggs in staged incubation within the cabinet and applying to them, in convenient arrangement for that purpose, a current of heated air, propelled by means other than convection. Staged incubation is the successive setting of eggs in the same cabinet at brief intervals of about three days. At the twenty-first day. there would thus be several settings of eggs in the incubator, each at a different stage of incubation, part in the endothermic

Page 6

stage and part in the exothermic. Smith arranged the egg trays or racks in tiers so that air could be freely circulated among the eggs. He subjected them to a continuous current of air of the requisite constant temperature of about 100° F. propelled by a fan so that it would circulate freely and repeatedly throughout the cabinet. The heat of the eggs in the later stages of incubation was thus carried by the circulating air of lower temperature to the...

To continue reading