Typical cases only can be taken, in number according to their [Illustration: CRIMINALS' WEAPONS: REVOLVERS, KNUCKLE DUSTERS, AND LIFE PRESERVERS IN THE BLACK MUSEUM. _Photo: Cassell & Company, Limited._] relative interest and importance, but all more or less illustrating and embracing the hydra-headed varieties of crime. We shall see murders most foul, committed under the strangest conditions; brutal and ferocious attacks, followed by the most cold-blooded callousness in disposing of the evidences of the crime. In some cases a man will kill, as Garofalo puts it, "for money and possessions, to succeed to property, to be rid of one wife through hatred of her or to marry another, to remove an inconvenient witness, to avenge a wrong, to show his skill or his hatred and revolt against authority." This class of criminal was well exemplified by the French murderer Lacenaire, who boasted that he would kill a man as coolly as he would drink a glass of wine. They are the deliberate murderers, who kill of malice aforethought and in cold blood. There will be slow, secret poisonings, often producing confusion and difference of opinion among the most distinguished scientists; successful associations of thieves and rogues, with ledgers and bank balances, and regularly audited accounts; secret societies, some formed for purely flagitious ends, with commerce and capitalists for their quarry; others for alleged political purposes, but working with fire and sword, using the forces of anarchy and disorder against all established government.