Vengeance on foes who strove to kill With blows well aim'd at heart or head-- Thieves that, with demon heart and will, Would fain have on they vials fed. O, They have blessed thee for thy aid, When grateful eyes, thy presence, spoke; Thou, anguish'd bosoms, glad hast made, And miser's tyrant sceptre broke. Now, when 'mong strangers, is our sphere, Thou, to my heart, are but the more Endear'd--as many a woe-wring tear Would plainly tell, if from me tore! There was little change in the mechanism of the spring lancet during the nineteenth century, despite the efforts of inventors to improve it. Approximately five American patents on variations of the spring lancet were granted in the nineteenth century. One patent model survives in the Smithsonian collection. Joseph Gordon of Catonsville, Maryland, in 1857 received patent No. 16479 for a spring lancet constructed so that three different positions of the ratchet could be set by the sliding shield. The position of the ratchet regulated the force with which the blade entered the vein. This also had the advantage of allowing the blade to enter the vein at the same angle irrespective of the depth to which it penetrated.[71] _The Decline of Bleeding_ Throughout the seventeenth, eighteenth, and nineteenth centuries, most physicians of note, regardless of their explanations of disease, including Hermann Boerhaave, Gerard Van Swieten, Georg Ernst Stahl (phlogiston), John Brown and Friedrich Hoffmann (mechanistic theories), Johann Peter Frank, Albrecht von Haller, Percival Pott, John Pringle, William Cullen, and Francois Broussais, recommended bloodletting and adjusted their theories to provide an explanation for its value. At the end of the eighteenth century and in the early nineteenth century, the practice of bloodletting reached a high point with the theories of F.-J.-V. Broussais (1772-1838) and others. After 1830, however, the practice gradually declined until, by the end of the century, it had all but disappeared.