Tin foil hat radio with a metal bucket. The AM radio is completely inside a metal enclosure. This leads to a noticeable reduction in signal strength received by the AM radio. The efficiency of a metal enclosure in blocking electromagnetic radiation depends on the thickness of the foil, as dictated by the "skin depth" of the conductor for a particular wave frequency range of the radiation. For half-millimetre-thick aluminum foil, radiation above about 20 kHz (i.e., including both AM and FM bands) would be partially blocked, although aluminum foil is not sold in this thickness, so numerous layers of foil would be required
Kitchen utensil utensils recommended to the aspiring householder in cookbooks as the century progressed. Earlier in the century, in 1828, Frances Byerley Parkes had recommended a smaller array of utensils. By 1858, Elizabeth H. Putnam, in "Mrs Putnam's Receipt Book and Young Housekeeper's Assistant", wrote with the assumption that her readers would have the "usual quantity of utensils", to which she added a list of necessary items: Copper saucepans, well lined, with covers, from three to six different sizes; a flat-bottomed soup-pot; an upright gridiron; sheet-iron breadpans instead of tin; a griddle; a tin kitchen; Hector's double boiler; a tin coffee-pot for