A question was asked about compacting soil. Soils vary from area to area. In my area Marlyand mid east coast. Soil is dense with clay and rock. When digging your bed for the foundation. Remove the sod, topsoil and any organic material. Digging down 4-6 inch depending on average thickness of your stones being using. Be sure to make your bed level and compact before setting stones. Dig as needed to make adjustments.
I'm able to do this since majority of jobs the soil has never been disturbed. The earth is very hard (compacted) In other cases if I have to add new soil or some kind of aggregate such as 3/4 stone.
I will need a hand tamp or more likely use a gas powered walk behind plate compactor.
Notes: Plate compactors will have different strengths of compaction. For example 3500lb centrifugal force. The one I use is rated 3000lb at 5500 vibrations per minute. Think of it as how much force you can apply with your hands pushing down on the ground. Then give it a rating. Some plate compactors even have such features such as water for better compaction with aggragrete. Others have reverse allowing one to walk into a corner and back out. With out having to do a circle. If you us aggregate for your base or new new soil you will need to compact the material to make the bed firm to place your stones. You can rent a plate compactor from the local rental shop. Plate compactors are simply one of many different types of equipment used for compacting materials. Other equipment used would be Jumping Jack, Drum Rollers...the list goes on.
Moral of the story if you are walking in 3 feet of fluffy snow with shoes you will sink. If you put snow moccasins on you will float on top. When using large stones for your foundation. They will not be likely to sink into the earth. They will act like snow moccasins and spread the load from above. They will also compact the soil as they settle over time.
Always use tools and materials to match your needs from region to region.