Les mentioned the problem of how long it might take to get up a head of steam in a cold engine. Of course they were aware of that problem and were able to design steam engines that could get pressure up within several minutes. Horse-drawn, steamer fire engines would have a full head of steam by the time they got to the fire, the tinder having been lit before they left the station. And the Stanley brothers boasted their steamer could heat up so fast that once you started the fire, if you let the throttle open just a little and walked down the block to the corner mailbox, your car would have caught up with you! I don't know that I'd want to take them up on that boast, but my guess is that by the turn of the last century, you'd need only about 2 or maybe 3 minutes to start operating a well-designed engine. Of course, it would also depend on the ambient temperature.

David