Smith & Wesson 2nd Model Bicycle trigger mechanism

[saahil]

hi members,
while surfing net i came across a amazing antique s&w wheel gun in .32 caliber. its a break open model with grip safety.(though i havent seen any s&w with break open system before).but the most amusing thing about this gun is its trigger mechanism,the thing which im not able to understand is how this trigger works,to fire do we have to pull it back or squeeze it upwardly.comments please. here are the pics.
http://www.collectorsfirearms.com/admin ... temID=4617