The following table is meant to be used by Mad Scientist characters in the early 20th century. Complete rules can be found in the Deadlands Players' Guide.
|Jacks||Current top-of-the-line technology, or simple repair of device created by these rules||Propeller-driven airplane; u-boat; radio; automobile; flame-thrower; automatic machine-gun||5||10-60 minutes|
|Two Pairs||Slight improvement on existing technology||10% faster automobile||7||1-5 hours|
|Three of a Kind||Major improvement on existing technology||Portable radio; rocket-propelled grenade||9||1-10 hours|
|Straight||Relatively simple but new use of existing technology||Helicopter; rocket-propelled car||11||1-6 days|
|Flush||New use of cutting-edge technology||Jet-propelled airplane; tilt-rotor aircraft||13||1-4 weeks|
|Full House||Entirely new but "realistic" technology||Rocket pack; primitive vacuum-tube computer; nightvision helmet; electric sound synthesizer||15||1-6 months|
|Four of a Kind||New technology that flaunts the laws of science||Heat or freeze ray; sleep gas; zeppelin aircraft carrier; gun laser sight||17||1-12 months|
|Straight Flush||New technology that alters the laws of science||Mind-control ray; anti-gravity vehicle; robot suit; x-ray vision helmet||19||1-4 years|
|Royal Flush||Technology that defies the laws of science||Dimension or time control device||21||1-20 years|
It's important to note that, even with the supernatural help of the manitous, there should be certain limits on what achievements Mad Scientists can easily make. First of all, while some Mad Science inventions can defy the laws of science, and do more than "conventional" machines of the time, they do so with the supernatural energy of ghost rock. In other words, despite all the "scientific" window-dressing, it's at least in part a product of magic. This is one reason why inventions of Mad Science defy attempts at mass production. The truly wondrous inventions are one-of-a-kind.
Please note that while a time control device is possible, actual time travel should be beyond the reach of Mad Scientists. Well, maybe the Marshal wants to do a time travel adventure. That's his business. But it shouldn't be an option casually made open to players if they happen to get some amazing die rolls and the cards turn out to be in their favor. The Reckoners had to go through a lot of trouble just to send Stone back in time, after all. Why in the world, then, would some petty little manitous and a mad scientist be able to outdo them?
Also, by definition, mad science inventions are large, clunky, and more or less unreliable in this period. As cool as it would be to run around with two-way wrist TVs, that would be over the top. (Even two-way wrist radios are pushing it.) Wait until the fifties or so before that may come around.
Ghost rock is still used for inventions, but "spook juice" has been developed, and that is frequently used to power machines. Steam power is a thing of the past. It's also conceivable that ghost rock might be employed in chemical reactions to power a device -- i.e., a chunk of ghost rock is stuck in a chemical bath, and the energies released as it dissolves are what powers the device. Irradiated ghost rock, however, is a thing still of the future.
Another important thing to keep in mind for inventions is a matter of style. A rocket pack in the 30s may functionally be very much like the rocket pack available in the 19th century ... but now it's more streamlined, with small hand-grips rather than a big awkward lever. Electrical devices tend to have lots of flashing lights of dubious purpose, vehicles may sport fins or chrome trim, and any mad scientist worth his blueprints is bound to incorporate an art deco touch here or there (or, if he's from the 1910s, an art nouveau touch here or there). Energy weapons have a tendency to sport long antenna-like needles with multiple rings running around them.