Thirty pounds? Although I am sure there were some with Yorkie backgrounds that big in the 1930's just as there are now, I don't think that was ever the norm for what we know as Yorkshire Terriers or their immediate ancestors the Broken Haired Toy Terrier.
This is from the Yorkshire Terrier by Joan Gordon:
History of the Yorkshire Terrier by Joan Gordon
"Yorkshire Terriers were given their breed name by 1874, although it had been around since 1870. Originally they were known and shown as Broken Haired Scotch Terriers or Toy Terrier (rough and broken haired).
Broken Haired Toy Terrier
Almost all of the classes were divided by weight. The classes were for Broken Haired or Rough Scotch Terriers less than 5 lbs. or 6 lbs. and under; Toy Terriers 4 lbs. and under, or 5 lbs. not exceeding 7 lbs., or 6 lbs. and over; or Blue Scotch Terriers under 7 lbs. or 7 lbs. not
exceeding 9 lbs. The largest weight class in which they were reported
to have been shown was for Broken Haired Scotch Terrier 9 lbs. not exceeding 12 lbs. This record should prove that although there were larger Yorkshires they were not being shown at the dog shows. The record proves that the small size was available for breeding from early days. "
I voted 4-7 pounds for safety sake, but I have to admit -- I would love to have a tiny little "under 3 pounder" as I think they are adorable. I know they have special needs, but I would gladly take on the responsibility. I guess that is why I keep having puppy withdrawal.