Wash and peel cucumbers.
Cut into 1/4 �?1/2 inch slices. Put in large bowl.
Cover the cucumbers with water. Sprinkle with the salt. Set aside for 2 hours.
In the meantime combine the vinegar, sugar and celery seed. Stir well to dissolve the sugar. Drain cucumbers.
Add onions and vinegar mixture to drained cucumbers.
Stir gently to mix flavors.
Cover and refrigerate at least overnight, so flavors can marinate together.
The cucumber salad flavors are even better after about 2 days in the refrigerator.