The curved projection (1) is the continuation of a heavy coiled spring. When pushed up it catches on a ratchet. A razor sharp blade (2), responding to the pressure of a light spring placed under it, follows the handle as it goes up. A lever (3) acting on a fulcrum (4) when pressed down, releases handle which in turn strikes the lancet down with lightning speed.[66] The spring lancet was initially described by Lorenz Heister in 1719.[67] Another early description appeared in 1798 in the first American edition of the _Encyclopedia or Dictionary of Arts and Sciences_, in which the spring lancet was called a "phleam."[68] The spring lancet for use on humans was a rather tiny instrument. Its casing was about 4 cm long and 1.5 to 2 cm wide. The blade added another centimeter in length. Larger size instruments, often with a metal guard over the blade, were made for use on animals. Eighteenth- and early nineteenth-century spring lancets are found in a wide variety of shapes. Mid- and late nineteenth-century spring lancets are more uniform in shape, most having the familiar knob-shaped end. In most lancets the blade was released by a lever, but in the late nineteenth century, the blade of a more expensive model was released by a button. [Illustration: FIGURE 6.--Spring lancet, 19th century. (NMHT 321636.01; SI photo 73-4236.)] [Illustration: FIGURE 7.--Interior of spring lancet. (NMHT 308730.10; SI photo 76-13535.)] In general, German, American, and Dutch surgeons preferred the spring lancet to the simple thumb lancet. In contrast, the French tended to prefer the thumb lancet. Ristelhueber, a surgeon in Strasbourg, maintained in 1819 that the simple lancet was preferable to the spring lancet both in terms of simplicity of design and application. While allowing German surgeons some credit for attempting to improve the spring lancet, Ristelhueber remained firm in his view that the spring lancet was too complicated and performed no better than the thumb lancet. The only advantage of the spring lancet was that it could be used by those who were ignorant of anatomy and the art of venesection. Untutored bleeders could employ a spring lancet on those veins that stood out prominently and be fairly confident that they could remove blood without harming other blood vessels. The bagnio men (bath attendants), who routinely bled the bathers in public baths, preferred the spring lancet.[69] It was more difficult to sever a vein with a spring lancet and thereby cause serious hemorrhaging. However, since the spring lancet was harder to clean because of its small size and its enclosed parts, it was more likely to induce infection (phlebitis). While the French and British surgeons remained critical of the spring lancet, it became popular in the United States. John Syng Dorsey, a noted Philadelphia surgeon, wrote in 1813: