Condensed Statements of Cash Flows (USD $)	9 Months Ended
	Oct. 31, 2013	Oct. 31, 2012
Cash flows from operating activities
Royalties received	$ 14,519,624	$ 25,004,610
Interest received	1,156	1,269
Expenses paid	(772,259)	(867,455)
Net cash provided by operating activities	13,748,521	24,138,424
Cash flows from investing activities
Maturities of U.S. Government Securities	240,000	35,000
Sale of U.S. Government Securities	100,012
Purchases of U.S. Government Securities	(82,380)	(205,054)
Net cash provided by (used for) investing activities	257,632	(170,054)
Cash flows used for financing activities
Distributions to Unitholders	(13,513,611)	(19,220,815)
Net change in cash and cash equivalents	492,542	4,747,555
Cash and cash equivalents, beginning of year	6,727,461	10,253,474
Cash and cash equivalents, end of period	7,220,003	15,001,029
Reconciliation of net income to net cash provided by operating activities
Net income	15,963,684	25,867,203
Increase in accrued income receivable	(2,190,369)	(1,562,211)
Increase in prepaid expenses	(35,783)	(55,167)
Increase in accrued expenses	10,989	(111,401)
Net cash provided by operating activities	13,748,521	24,138,424
Non Cash Financing Activity
Distributions payable	$ 6,691,205	$ 14,825,611