The first burglar alarm was installed this day in 1858. It marked our transition from protecting property with lock and key, to a more sophisticated means of foiling intruders. Today, 17 percent of homes have a pro-installed system -- doubling the number of 10 years ago. But what about the other 83 percent that don't have alarms? There are 2.1 million home burglaries every year, and experts say 90 percent of them could be prevented. Many are crimes of opportunity committed by amateurs. Most are first-floor break-ins aided by unlocked windows and doors, and they occur in daytime rather than at night. Good locks and deadbolts are a must. While most know prevention basics like motion-sensor lights, timers and stopping your mail when away, shifty burglars look and listen for other signs such as an answering machine that says "we're away." Even if you don't have a dog, a beware of dog sign or a bone and a big doggie bowl by the door might be deterrents. And that's the On The House tip for today.