• The bond energy for H 2 is nearly twice as large as that for H + or He 2 + .
• The double-acting compressor discharges twice as much fluid per cylinder as the single-acting.
• The distance between the objectives is twice ( or double ) that between the eyepieces.
• The length of the geosyncline should be more that twice its width.
• The total capacity of these steam fields is only about twice what a single nuclear power plant develops.