Just ordered some 3-way lightbulbs for my office.
They are too tall to replace the 70w bulb in the lamp!
They are 50-100-150. If I order 30-100’s, will they be shorter, and thus fit in the lamp?
Oh, for the love of Jehovah. I just found “short” 3-ways on the web. (And no, not the porn.)
Nevermind.
Pardon me, but what exactly is a 3-way light bulb?
A three-way light bulb has two filaments inside. The lamp has a switch which can turn on one filament or the other or both. The 50-100-150 bulb mentioned in the OP has a 50-watt and a 100-watt filament, and when both are on the total draw is 150 watts.
Well, at least my ill-thought-out post has done some good towards the fight against ignorance!!! 
Intertesting… what fitting are they and how are the (presumably multiple) contacts arranged?
I guess they should be called four-way bulbs though: 00 01 10 11
Ummm… you’re jumping from 70W to 150W. That’s a lot of extra heat. Make sure the lamp is rated for 150W.
Peace.
Three way bulbs add a ring contact between the threaded shell and the center tip.
Does Europe still use primarily bayonet-style sockets? (Push straight in and engage the pins with a slight twist) If so, you’re probably unfamiliar with our screw-in bulbs. Here’s a picture of a North American 3-way bulb.
No, although they still exist. (They might still be popular in UK. I think I’ve seen some there.) In continental Europe (at least Germany, Switzerland, Sweden and Norway) E27 bulbs are the norm. I’ve never seen three-way ones though.
Pity, it seems like a neat idea.
Bayonets are still by far the norm in the UK; they come in normal and small (SBC) varieties. Screw-type lamps (they’re known as Edison Screw - hence ES and SES (small Edison Screw) are available, and some table lamps take these, but they’re not the norm…
Then you have to refer to normal bulbs as 2-way bulbs…
I’ve never seen a 3-way bulb in Japan either, though the same E26 socket as the US. (I think E26 is the 100V version of E27?)