2 Christmas lights were invented as a result of a near ly 1.__ tragedy. Before first electric tree lights were 2. ___ used, people used candles to decorate our trees . 3.____ The wax candles were not safe.There were hundred of cases of children knocking over the 4. ____ beautiful pine trees and were badly burned or set- 5.___ ting fire to the house. Adults often received minor burns while lighting the small candles. If a candle f all out of a holder, the dry pine needles would go 6. __ up in flames in seconds. In 1907, Ralph E.Morris , a telephone worker in Cambridge, Massachusetts, almost lost his son when the little boy crawled under the tree and upsetted it. Fortunate- 7. __ ly, Morris was able to pull his son away since the 8. __ boy was seriously burned. He decided that some- thing must be done to change the custom. The next year he bought dozens of little telephones 9. ___ switchboard lamps, soldered them to a pair of long wires, and covered them with colored paper. Later, colored glass , that ma d e the lights safer , 1 0. ___ replaced the paper .