> db.measurements.find()
{ "_id" : ObjectId("53203553666661072f000000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:00:00Z"), "wh" : 1234136 }
{ "_id" : ObjectId("53203553666661072f010000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:01:00Z"), "wh" : 1234149 }
{ "_id" : ObjectId("53203553666661072f020000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:02:00Z"), "wh" : 1234162 }
{ "_id" : ObjectId("53203553666661072f030000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:03:00Z"), "wh" : 1234175 }
{ "_id" : ObjectId("53203553666661072f040000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:04:00Z"), "wh" : 1234188 }
{ "_id" : ObjectId("53203553666661072f050000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:05:00Z"), "wh" : 1234201 }
{ "_id" : ObjectId("53203553666661072f060000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:06:00Z"), "wh" : 1234214 }
{ "_id" : ObjectId("53203553666661072f070000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:07:00Z"), "wh" : 1234227 }
{ "_id" : ObjectId("53203553666661072f080000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:08:00Z"), "wh" : 1234239 }
{ "_id" : ObjectId("53203553666661072f090000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:09:00Z"), "wh" : 1234252 }
{ "_id" : ObjectId("53203553666661072f0a0000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:10:00Z"), "wh" : 1234265 }
{ "_id" : ObjectId("53203553666661072f0b0000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:11:00Z"), "wh" : 1234279 }
{ "_id" : ObjectId("53203553666661072f0c0000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:12:00Z"), "wh" : 1234293 }
{ "_id" : ObjectId("53203553666661072f0d0000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:13:00Z"), "wh" : 1234308 }
{ "_id" : ObjectId("53203553666661072f0e0000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:14:00Z"), "wh" : 1234322 }
{ "_id" : ObjectId("53203553666661072f0f0000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:15:00Z"), "wh" : 1234336 }
{ "_id" : ObjectId("53203553666661072f100000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:16:00Z"), "wh" : 1234349 }
{ "_id" : ObjectId("53203553666661072f110000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:17:00Z"), "wh" : 1234362 }
{ "_id" : ObjectId("53203553666661072f120000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:18:00Z"), "wh" : 1234375 }
{ "_id" : ObjectId("53203553666661072f130000"), "meter_id" : 1, "timestamp" : ISODate("2014-03-12T00:19:00Z"), "wh" : 1234388 }
...