A total of 58 law firm mergers and acquisitions have been announced through the first three quarters of this year — a 41 percent increase over a year ago. MergerLine, a service of the legal industry consulting firm Altman Weil Inc., also reports that 19 firm combinations occurred in the third quarter alone, a slight increase from the same period in 2012. “Law firms are looking high and low to find lawyers with good clients that they can acquire,” said Thomas S. Clay, a principal at Altman Weil …