I watched a documentary "Man vs Wild" which showed the TV presenter Bear Grylls collecting wood and starting a fire. He somehow always manages to keep his campfire burning until dawn. How does one know how much wood to collect such that it is adequate to last throughout the night? Is there a certain method of arranging the wood pile consisting of broken branches and twigs to maximize the period of combustion?
It's difficult to tell exactly how long wood you've gathered will last you, unless as an expert you can gauge an accurate estimate due to the type of wood, weather conditions and other contributing factors (theoretically possible, but above my ability level.)
However, there are different ways of constructing a fire, and one in particular is designed to burn for long periods, such as overnight, without requiring any maintenance or fiddling about through the night (if done correctly.)
This is known as a pyramid fire:
You place two logs parallel on the ground to start with, then place a row of smaller logs perpendicular and on top of the original two, then another row perpendicular and on top of that row, and so on. You then light the fire at the top, and instinctively quite bizarrely the fire will then burn downwards (as each level becomes hot enough to ignite the layer below it.)
Image taken from here.
To get a long lasting fire, you have to limit the cumbustion somehow. Think embers as apposed to much flame.
Wood stoves are specifically engineered to allow you to control the rate of combustion. This is done by controlling the air intake to the fire, which limits oxygen, which limits the combustion rate. A wood stove can be built nicely sealed, so the biggest problem is providing enough oxygen to keep the fire going.
In the wild, this is much more difficult as you don't have a nicely sealed fire box with a single air intake you can control. The best you can do usually is to emulate a fire box with rocks and stuff up some of the openings with mud and the like. Still, there will be more oxygen than necessary to just keep the fire alive. There is little alternative to keeping a supply of wood ready and feeding the fire periodically if you really want to sustain a fire.
However, consider whether a sustained fire is really necessary. You can build something with at least somewhat limited air intake, give it a supply of relatively large pieces of wood, and surround it with lots of rocks. Even if the fire goes out, the rocks will stay warm for quite a while. A better strategy is to not require a fire all night long, especially if you are in a place and conditions where the fire could escape if you don't watch it.
Additional to the other tips and warnings I would like to mention one special tecnique I found in the book "Outdoor Praxis" by Rainer Höh.
Basically it consists of some kind of reflector fire, but the reflector will feed the fire instead. You would stick two or more thick, maybe even green, branches in the soil to support the reflector. Make sure to incline them away from the fire - while this makes the reflector less effective it allows self-feeding. Now pile your firewood up reclining onto the support sticks. Make/move your fire close to the reflector so the one at the bottom starts to burn. While it is burned up, the pile of wood will slip down, allowing the next branch to burn. This works probably best with wood 5-10cm in diameter. Smaller ones will burn to fast, thicker ones wouldn´t start burning easy enough.
Please note that this needs some practice and doesn´t garantuee that the fire will burn overnight. Still, its better than nothing. If you want to use it for staying warm its perfect, because you can stretch it and it has at least a little reflector.
Illustration (not quite what I am suggesting, since this reflector here isn´t meant to burn and the support sticks would be way to thin, but its similar):
Image taken from www.survivalistssite.com
In one of the series of Survivorman the Les Stroud has put into fire the whole fallen pine. A very thick trunk will burn for a long time. Generally, the thicker the wood the longer it will burn. A thin branch will last a few hours, the fire will not be big, but it will nevertheless give heat.
Unfortunately I never recorded it, but as far as I remember a very thick branch was burning for a few hours. When it is cold, you wan't sleep the whole night, you would wake up often and you can adjust the campfire then. It's the way Bear Grylls probably manages that, if not helped by the camera crew ;) He almost always make shots in dark saying how cold it is and how bad he sleeps :)