Later, Irwin improved upon this design by inventing and . This design is similar to his earlier "hot-blast" design, except that the oxygen-depleted hot combustion byproducts are redirected and prevented from recirculating back to the burner by redesigning the intake products, so that only oxygen-rich, fresh air is drawn from the atmosphere into the lamp ("the inlets for fresh air are placed out of the ascending current of products of combustion, and said products are thereby prevented from entering air intake"). The primary benefit of this design compared to the earlier "hot-blast" design was to maximize the amount of oxygen available for combustion by ensuring that only fresh air is supplied to the burner, thereby increasing the brightness and stability of the flame.