The base rules for Tempus Fidgit can be found here: http://faterpg.com/dl/sotc-srd.html
Of course, there are a few modifications for setting specific details.
1: The drive skill is removed, subsumed by pilot, which applies equally to all forms of self-propelled vehicles. Survival covers things like horse-drawn carriages, though pilot might be substituted if, say, the horses in question are clanks.
2: Starting characters get the standard 10 aspects, and the standard skill tree, but get eight stunts.
3: Certain aspects (most typically The Spark) may be taken more than once. Any such aspect must have reasonably common uses for both invocations and compels. Further, any such aspect must represent part of the core concept of the character - for example, a warrior who also happens to be a spark, is unlikely to qualify for The Spark x2, let alone The Spark x3. This generally means that you can't have more than one aspect that's stacked up like this. Three of any given aspect is also the maximum.
The effect of this is as follows:
At x2: Invocations of the aspect grant +3 to appropriate rolls, and declarations can be a bit more dramatic than normal. Compels of the aspect cost two fate points to buy out of. (But still only grant one fate point if you accept the compel.)
At x3: Invocations of the aspect grant +4 to appropriate rolls, and declarations can be fairly far out there. On the other hand, buying off compels now costs three fate points. (But still only grant one fate point if you accept the compel.)
4: Special rules for The Spark. One level of The Spark gives you the weird science stunt for free... if you have all the normal pre-reqs for that stunt. Two levels, and you get mad science on top of that. Three levels, and you get a second mad science stunt, granting you two different specializations for your ability to make the laws of nature jump through hoops.