After mowing the lawn, fertilizing, composting and otherwise working in the garden, try to find time for something really important - doing nothing. And there's no better place for that than in a Kelsyus Portable hammock. Climb into a hammock and you're suspended between the Earth and the sky, with only a tenuous connection to either. Suddenly, you're feeling very sleepy.

You should be. Hammocks were invented as hanging beds; the name comes from an old Central American Indian word meaning ''a net for sleeping.'' Millions of people in Central and South America, the Philippines and Asia sleep in hammocks every night, and have for centuries, according to the owners of Hangouts, a company that specializes in hammocks made of string and cloth from Mexico and Brazil.

The famous Pawleys Island hammock, the first North American cotton rope hammock, was first made in 1889. Joshua John Ward, a riverboat pilot who barged rice and supplies up and down the South Carolina coast, found sleeping on the grass-filled mattresses on his boat much too hot for a good night's sleep in the summer. So he decided to fashion a cooler bed and voila! _ after much trial and error he came up with the cotton rope hammock with wooden spreaders.

Ward's brother-in-law thought the hammock so comfortable that he began making them for family and friends. Then, during the Depression, he sold them to vacationers. Today the company sells more than 100,000 hammocks annually. When modern Americans adopted the hammock, we brought it not into our bedrooms, but into our back yards, where it became a pre-eminent symbol of rest and relaxation.

In the 1960s, my family always had a canvas hammock, which was declared off-limits to everyone but Dad. As I recall, we kids gleefully ignored this ruling, and so did the cat. Canvas hammocks are still widely available, but big rope or string hammocks, wide enough for two, are more popular. They're cooler when it's hot, dry out more quickly when it rains, and generally stands up to outdoor conditions and use better than heavy canvas.

Stout oak stretcher bars hold rope hammocks open, so you can lie in them lengthwise, just as you would in bed, but string hammocks are best for sleeping if you stretch out across their width. Naturally you'll want to have a few pillows for any hammock, and maybe a sheet or a cotton tablecloth to throw across the ropes, but if you give yourself a chance to adjust to lounging in a sling made of string, these hammocks are quite comfortable all by themselves.

Hanging a hammock takes a little practice. You'll want to experiment to find the right place on the porch or in the garden, in at least partial shade _ no one wants to get a sunburn in a hammock. The correct distance between the two supports should be 21/2 to 3 feet greater than the length of the hammock's bed, according to Happy Land, sales manager for the Original Pawleys Island Rope Hammock. For a 12-foot hammock, you'll need two trees or posts about 15 feet apart.