A very fine Jansson sea atlas coming up at Arader Galleries auction on September 25, 2021.

 Joannes Janssonius.  Atlantic majoris quinta pars.  Amsterdam, 1752.  

This masterpiece is complete for this edition and has a spectacular original binding with very fine mid 17th century color. 

This atlas has appeared twice at auction in the last 50 years.  One was ok with original color and made 56k 25 years ago but incomplete with only 23 maps and the other was uncolored and made 23.2k 10 years ago with 33 maps.  Color is very important for the Dutch maps of the Baroque Period.  So my feeling is that 90k is a conservative estimate of the current auction value but the IRS donation value would be in the 200k range.   So my suggestion for a bid would be 75k which with the 20% premium would be a cost to you of 90k well under its true value.  You would have a reasonable chance of getting this as long as other bidders possess sense.  As you know already, that does not always happen.  The break value of the 33 maps is well over 225k.  The map showing Florida and the Bahamas would be worth $35,000 alone today.  

This book demonstrates why the Netherlands became so rich - sea trade.  And of course it was published only four years after they finally (the War lasted 80 years!) achieved independence from Spain at the Treaty of Westphalia in 1648.  The maritime world was theirs until Napoleon bottled up their fleet frozen at anchor on January 23, 1795 with his cavalry.  Dont think that happened at any other time in Naval History!  

Here are the auction records referenced above:

	Janssonius, Joannes - Grooten Atlas. Amst., 1652 - Jansson, Jan - With 23 double-page charts & maps with contemp hand-coloring. - Staining at lower corners - Sotheby's, Dec 4, 1997, lot 226, £27,000 ($44,812) plus 25% commission = $56,015 - Koeman IV,Me 169A
	Janssonius, Joannes - Cinquiesme partie du grand atlas.... Amst., 1650 - Folio, - Jansson, Jan - orig vellum - With 33 plates - Sotheby's, May 9, 2012, lot 104, £12,000 ($18,607) plus 25% buyers commission = $23,258. - van der Krogt 1:4165M&O; Koeman Me 171