After an unsuccessful attempt to sell the family secret in Paris, Hugh Chamberlen found a purchaser in Amsterdam. The privilege of using it in Holland was then granted physicians for a monetary consideration, and that practice continued until two philanthropists purchased the secret to make it public. It was ultimately learned, however, that the sale was a swindle, for the device which the purchasers obtained consisted of only half the genuine instrument. The real secret was revealed by a son of Hugh Chamberlen, who bore the same name as his father; but probably the first accurate printed description of the forceps was made by Samuel Chapman, in his treatise on obstetrics which appeared in 1733. Subsequently they came into general use, and, with many modifications, remain the most important instrument in the obstetrician's equipment. There can be no exaggeration in the claim that the instrument has done more to save human life than any other surgical appliance. The obstetrical forceps have been of such great service in diminishing the number of still-born infants that they were once called the child's instrument. The need of its employment in behalf of the child may be determined by careful observation of the fetal heart-sounds, which are heard over the mother's abdomen, and by means of which one may learn the condition of the child. Signs of danger are extremely uncommon so long as dilatation of the womb is not complete, for any strain which labor may impose upon the child will usually occur during its passage through the pelvis. Most often, therefore, the head has reached the outermost part of the birth canal before extraction becomes advisable.